Neptune, which rules Pisces, takes 146 years to complete a circuit through the Zodiac, staying in each sign for approximately 14 years.  This is another planet that has a generational influence since everyone born during that 14 year period will have Neptune in the same sign.  However, since House placements depend on the time of birth, it will affect different areas of the individuals' lives, even though collectively they're in the same sign.  If that's clear as mud keep reading.  I think the meaning will become apparent when you read the influences in the different houses.  Remember that in spite of what Sign a planet is in, the house placement will depend on the time a person is born. 

If you look at the periods when Neptune was transiting the different signs over the past century or so you can see predominant themes emerge.  These will be covered below for the relevant signs, i.e. Cancer (1901/2-1915), Leo (1915-1928/29), Virgo (1928/29-1942/43), Libra (1942/43-1956/7), Scorpio (1956/7-1970/71), Sagittarius (1970/1-1984/85), and Capricorn (1984/5-1998).  Children born from 1998-2010 will have Neptune in Aquarius and it's too soon to determine how that influence will play out.  No one living can have Neptune in Pisces, Aries or Taurus and very few remain with it in Gemini, which covered birthdates from approximately 1886-1901.

Neptune's influence tends toward inspiration and introspection on the one hand but clouds and confuses to the point of deception on the other.  When Neptune is retrograde intuition is strengthened and, depending on its house and transit placement, will tend to confuse logical arguments in favor of gut feelings.

1st House/Aries:  If Neptune is within approximately 8 degrees of the Ascendant it will have a strong influence and tend to cloud the characteristics of the sign itself with Neptunian traits.  Those who have it in the 1st House will generally have difficulty getting organized and tend to make excuses for any lack of success.  Taking the easy way out and letting others handle any problems is likely.  (Neptune will not transit into Aries for approximately twenty years.)

2nd House/Taurus:  Attitudes toward money and possessions will tend to be quite magnanimous.  These individuals will be a soft touch for hard luck stories and be perhaps too generous and quick to help others financially, sometimes to their own detriment, unless countered by heavy Earth influences.  Those with this placement need to make a concerted effort to hang on to their resources and have someone they trust who is more practical help them make financial decisions.  (Neptune will not transit Taurus for approximately another thirty-five years.)

3rd House/Gemini:   This is the House of the mind and thought processes and Neptune's presence here will tend to cloud and confuse logical thought while enhancing imagination.  Imaginary friends and lack of attention coupled with difficulty in school are likely for children with this placement.  Artistic talent is likely, but finding the discipline to direct and develop it may be difficult.  Some astrologers believe that this placement enhances the voice so the individual may have a talent for singing.  (Neptune will not transit Gemini for approximately another fifty years.)

4th House/CancerNeptune in the 4th House often relates to childhood experiences, perhaps growing up in a home that stimulated the imagination, either due to an unusual environment or perhaps as an escape from domestic problems.  In adulthood it can tend to make the person want to create an ideal home or environment that is not in synch with reality.  (Those born from 1901/2-1915 had Neptune in Cancer.  There was a tremendous amount of disruption and confusion among families and homes during this time due to men being killed during World War I as well as illness including a flu pandemic.  Between 1905 - 1911 Uranus in Capricorn was opposite Neptune, compounding these unfortunate effects.  Along these lines, the Titanic sank in 1912, under similar aspects.)

5th House/Leo:  Neptune will definitely turbo charge any creativity associated with this house, which will most likely be colored by its sign placement.  The caution here lies in the tendency to fall in love too easily and then maintain unrealistic expectations for the relationship.  The heart will rule the head and much foolishness in the name of love can result, ultimately causing a lot of hurt.  This same attitude can be expressed toward their children, i.e. having unrealistic expectations for them or trying to live out their own dreams through their offspring.  (Neptune was in Leo for those born from 1915-1928/9.  During this time the movie industry was in its infancy with the silent film era.  Tough times were still afoot with WWI and the Great Depression in 1929 and people welcomed this escape into a fantasy world.)

6th House/Virgo:  The Neptunian imagination could have a detrimental effect on the person's health, predisposing them to hypochondria, allergies and various vague ailments which most likely will not respond to conventional medical treatment.  In the workplace there will be numerous challenges such as a persistent tendency to daydream, lack of discipline, perhaps absenteeism (due to the previously mentioned physical ailments) and missed deadlines.  Attaining an education in a creative profession so they can find  suitable employment later is advised.  (Neptune was in Virgo from 1928/29 - 1942/43.  The movie industry continued to progress with sound being added at this time, showing the strong influence of Mercury-ruled Virgo's communication enhancements.  Inventions such as radio also improved communications and provided entertainment via dramatic presentations that also provided escape into a fantasy world, if only for a few minutes each day.)

7th House/LibraThis placement, depending on the Sign, can predispose the person to preconceived notions about relationships that are entirely out of synch with reality.  They'll have a fairytale view of romance and, while they'll do a good job creating a romantic and imaginative environment for their partner, they're also likely to be very disappointed when real life doesn't match their expectations.  They're also unlikely to share responsibilities involved in running a household so their partner will be forced to handle more than their share, which could strain the relationship.  (From 1942/3 - 1956/7 Neptune was in Libra.  This was the post-WWII era and everyone was ready for peace.  These folks grew up and became the "flower children" of the late 60s and early 70s.  They sought for an easier life style, smoked a bunch of pot and thought that everyone ought to get along.)

8th House/Scorpio:  This placement will add considerable intensity to the sexual nature.  The individual is likely to have a tremendous amount of allure (possibly to both sexes) but the possibility also exists for Neptunian confusion in this area.  In the financial arena, they will tend toward the same generosity as with 2nd house placement, but this time it might be someone else's money they're giving away.  Either that or they're the person with the "hard luck" story who is vying for assistance from anyone they can convince to help, perhaps using some of those talents of seduction previously mentioned.  (Neptune was in Scorpio from 1956/57 - 1970/71.  This was when hard rock music came into its own and a new aggressive and sexual theme came into society in general.  With it came the advent of easy and reliable birth control and the abortion issue.  Many in the forefront of gay rights issues were born during this time.  The inability to cope with life and thus use drugs and alcohol to escape also increased during this era.)

9th House/Sagittarius:  Neptune has the potential to have a positive influence in this house.  It will lend inspiration and idealism to the person's intellectual pursuits and may even provoke interest in mystical or spiritual subjects.  It is likely that any travel abroad will be tremendously inspiring and may also provide for some strange or even weird experiences.  Very vivid dreams and strong recall are also likely.  (Neptune was in Sagittarius from 1970/71 - 1984/85 so this generation is just now coming into its own.  Themes toward idealism and Neptunian views toward society seem to be emerging, though on the negative side these can be seen as an attitude of entitlement that lacks practicality.  This generation seems to be living at home dependent on their parents much longer than previous ones and shows a general resistance to accepting responsibility of their own.)

10th House/CapricornIn the 10th House of status and reputation, particularly if conjuncting the Midheaven, Neptune could indicate a very charismatic individual who makes all the right moves to achieve high standing in a field related to the resident sign.  They are likely to be imaginative or perhaps inspired and thus inspirational to others.  These could be visionaries with high aspirations, though it is possible that they may lack a true sense of direction and may change their paths numerous times during their lifetime.  On the negative side, they could also be masters of deception. (Neptune was in Capricorn from 1984/5 - 1998 so the jury is still out as far as the accomplishments of those born during this timeframe.  Historically, however, we had numerous events that are somewhat telling.  Environmental issues have definitely come to the forefront (Capricorn is an Earth sign).  On the political side, deception has been on the increase worldwide and the quest for status on the part of individuals, countries and organizations has been apparent.)

11th House/Aquarius:  An individual with Neptune in the 11th House of group interaction will probably interact socially with individuals of an unusual or creative nature.  They will use their social circle and activities to escape the humdrum nature of their lives and find at least temporary relief from their looming responsibilities.  However, they need to make sure that they see these people as they really are and not expect too much from them in time of need.  They should also exercise caution that they not be used by others.  These folks may also find great satisfaction in charitable work.  An historical figure with this placement is Wolfgang Amadeus Mozart.  (Neptune has been in Aquarius since 1998 and will remain there until 2010.  While Aquarius lends humanitarian inclinations, the Neptune influence could infuse more sensitivity and genuine caring.  With the numerous natural disasters that have been occurring worldwide the past several years, there will be ongoing opportunities to exercise these activities.  However, I can also see more of that Neptunian entitlement attitude emerging that implies that society bears total responsibility for taking care of the individual instead of vice versa.)

12th House/Pisces:  Since Neptune rules Pisces, this is its home base.  Time for introspection and creative renewal will be important to this individual.  It is a good placement for those that work in public service professions since it enhances intuition and caring which will assist in providing genuine help to their constituents, whoever they might be.  With negative aspects, there is also the unfortunate possibility of self-deception or an escapist attitude which the person will need to keep close tabs on, possibly thru a very realistic friend or confidant.  (Neptune will enter Pisces sometime around 2010 so we ain't there yet, but it's coming up fairly quickly.  I suspect that what we'll see is a lot of genuine good work being done on the humanitarian level but that we'll also see a tremendous amount of confusion in public policy issues.  We'll see a new high in deceptive practices, whether at the government or corporate level, and all those blood suckers looking for a free ride will be louder than ever.)