A Google search for "Wodehouse" yields close to a quarter of a million hits. A handful are excellent, most are dross. Below is a list of my favourites.
Societies
The principal societies in the English-speaking world are The P G Wodehouse Society (UK) and its US counterpart, The Wodehouse Society. The web-sites of both offer a lot of material, including book reviews, news items about Wodehouse, and details of forthcoming events; the UK society's site also has, for those who enjoy such things (I don't!), a regular quiz.
Societies in Russia, Belgium and the Netherlands also operate websites that have varying amounts of information. The Russian site, in particular, has lots of 'goodies', for those willing to spend some time browsing its pages.
Discussion Groups
For those who wish to enjoy the virtual society of like-minded people, two email-based 
groups are worth considering (I should declare an interest, as I'm a member of both groups and a founder member and moderator of the first):
Blandings has over 250 members, drawn from as far afield as Australia, Canada, France, India, Ireland, Israel, Malta, the Netherlands, South Africa, the UK and the USA. As well as participating in the discussions, Blandings members have taken part in a number of collaborative projects: the annotations included here grew out of one such project, while another has unearthed and made publicly available several hard-to-find Wodehouse works that, at least in the US, are no longer under copyright protection.
The other group, WodehouseIndia, has fewer members and, as its name suggests, attracts primarily Indian fans, but non-Indians are made very welcome; there is, in fact, a lot of overlap between the two groups. Indian residents of WI frequently gather for informal meetings, and, for the past three years, have also organised a more formal annual 'convention'.
Discussion in both groups ranges from the profound to the trivial and – it must be said – those who have a decided preference for (or against) one type of discussion do not always find the environment quite to their liking. Also, some members find the volume of emails overwhelming (though a daily digest option is available for those who are unable to handle a daily inflow that rarely exceeds a couple of dozen messages).
Google Earth 
Google Earth (GE) offers opportunities for presenting a wide variety of information in an entirely new way. If you have GE installed, a visit to Hetty Litjens's Wodehouse Project is well worth while. It identifies a great many locations that were associated with Wodehouse or are referenced in his work, and is an excellent complement to my annotations (and vice versa).
Other Sites
One of the most interesting is Biblia Wodehousiana, a site devoted to identifying and explaining the innumerable Biblical references in Wodehouse's work. The author, another active member of Blandings, has also organised a Wodehouse webring.
Another site which I had unaccountably overlooked is Blandings. which "aims to cover subjects that other Wodehouse sites miss". With pages devoted to such topics as English money, Public Schools, Sports, and the English county system, it succeeds in its aim!
"Jeeves & Wooster at The Hat Sharpening Shop" is devoted to Granada's TV's "Jeeves & Wooster" TV series and has a wealth of information about the series, the period, and the J&W stories in general.
A P G Wodehouse Coverage is a gallery of Wodehouse book covers from publications in two dozen languages, from Bulgarian to Turkish.
Neil Midkiff's site has by far the most comprehensive on-line listing of Wodehouse's short stories. He has also written, for the Drones Club, an interesting article on 'racist' epithets in Wodehouse's work.