I am a huge fan of NEHGS - The New England Historic Genealogical Society. I volunteer for them as an Ambassador (the only one in Delaware) and doing transcription work for their website. I support them in financial ways when possible, not just with my $75 per year membership, but by sending them an additional donation each year.
When it comes to NEHGS, I simply can not express in words how wonderful I think they are. First of all, here is a society dedicated to New England Genealogy. Not only do they have a library of books, microfilms, manuscripts, and more (and I am SO looking forward to my visit to it), but also they have made huge amounts of vital records and more available through their website.
Members researching long distance, such as myself, enjoy this benefit immensely. When I grew up in Massachusetts, it was no problem for me to walk to the Bridgewater Town Hall and ask for the birth certificate of a great-grandmother who was born in 1832. But when we moved to Delaware in '99, I became one of the majority of long-distance genealogists.
In addition to their splendid website and library (again, I can't wait to spend a day or two there!), NEHGS has two of the best publications for New England genealogy - "The Register" which is a scholarly journal dedicated to New England families, and "New England Ancestors", the well-written magazine full of articles about New England records, how-to's, specific religious groups, towns, and more.
"The Register" is basically a quarterly collection of genealogy reports on new discoveries or corrections on established New England families, and although the reports may seem boring to read unless your own ancestor is mentioned (which I probably have happen once or twice a year), it's actually a very useful journal. One article recently demonstrated how deeds revealed the maiden name of a woman in Bolton, Connecticut, whose descendants were well-documented, but whose parentage was unknown.
These reports illustrate the efforts of the researchers and serve as inspiration for me.
Well, I had best get back to the volunteer project I am working on for NEHGS at this moment. It is a real pleasure to be able to give something back to my favorite genealogical society.