I wouldn’t stoop to being a member in any club that would let someone like me in! 
I tried to start a chapter of AA, but they wouldn’t let me hold meetings in the bar.
They wouldn’t let me be “Best Man” at an all-girls school.
“The sign says ‘No Homers’. We already got one!”
AMORC
Ah, my high school days…
Latin Club - Non-dues paying member
Meritless Humour Society (On a sign it looks almost like NHS. There’s a running gag on that)
Set Club (Just an excuse to get together after school and play various gameshow-type games)
Thesbian Club - Non-attending member
Cross Country - The roughinest, toughinest of all high school sports. I’m lookin right at YOU, Football.
And I was also the founding member of our chapter of the Veterans of Future Wars.
Oh, and I quickly approacheth One Thousand posts. Shit, I gotta come up with a freakin’ speech or a great new catchphrase or something fast!
Thanks for all the suggestions! I do have one question though—where can one find out information about clubs/organizations in their city? I’ve tried looking through Google, but I wasn’t quite interested in the listings and I know there has to be much more. Someone mentioned once going to the Chamber of Commerce. Would they have a list?
Magickly Delicious, you mentioned community theaters. Do they normally let anybody in who is interested? I always got the impression that most community theaters were set up through local colleges and the colleges’ acting classes. But that may just be part of my imagination!
I know that the local radio stations are great for announcements of meetings of clubs and stuff. Also, find your local newspaper/tv station website–they often have a ‘community calendar’.
I know my local community theater will pretty much let in anbody to do crew-type stuff. As long as you can make the time commitment, although I haven’t done it myself yet. My community theater is pretty independent and has no link to the local college. Um, darnit, it has no website, but try here as a starting point to find local theaters.
bean, the local theater-fine arts center is sponsored through an organization/members, not by the university and community college (they have their own fine arts organization). You have to pay to be in the membership, but you get discount tickets for the foreign films they show and tickets for some of their productions.
I’m a member of AOPA, but I know that’s not the kind of organization the OP means. I used to be in the Civil Air Patrol. I might join an MG owners club once my car is restored. Of course, I’m a member of The Straight Dope Message Boards and interact with Dopers online and IRL.
I’m a member of the Society for Creative Anachronism, also known as the SCA, a medieval re-creation organization that promotes learning about pre 17th century history. Oh, and its also a good excuse to beat up your friends with sticks and drink beer. Good times…
Hmm…
The Direct Marketers Assn (Our motto: We inundate you!)
The Elongated Collectors (A squished penny group)
Amnesty International, does that count?
Heh. I have a penny that was flattened by the Freedom Train back in '76. (Had I been thinking, and if I wasn’t just a kid, I should have used a Bicentennial quarter.)
I am an active member of Celebrate Brooklyn.
My husband is on the board of The Prospect Park Alliance and I participate in the Prospect Park Community Committe (affectionatly known as “com com” by the rest of the Alliance.
My husband is also on the Board of Directors of FAC and I do plenty of volunteer work here.
I also belong to Romance Writers of America.
When I was in college I was the Brooklyn College chapter secretary of MYPIRG. Now I just send them money and go to their cool events. They don’t have much use for us non-college students outside of staff.
That should be NYPIRG and not MYPIRG. I previewed and everything.
Green Party
John Birch Society
PTA
hee hee
You can bet your sweet ass that I’m in the Turtle Club.
Vanilla, you are EVIL. Gotta love it!
O
SCA
NRA
RPGA
I’m a nerd and I’m armed, damn it!
With both blades and firearms, no doubt. 
I’m heavily involved in a LARP (Live Action Roleplaying) group called the IFGS (International Fantasy Gaming Society). There are many others, and most of them are good fun with interesting people. I think the Vampire LARP is the most widespread, and involves the least physical effort. Basically, LARPing is a sort of large-scale improvisational acting, sometimes with costuming and combat thrown in. You make up characters (based on the guidelines of the game), and get together with other players in costume and in character to do things. I recently described an IFGS game I ran as “a play in which half the cast knew their character, but not their lines, and the other half was pulled from the audience at show-time”.
Shameless plug: Try www.ifgs.com to see if there’s a chapter near you. The links page also has links to some other LARPs.
Technically, that would be a ‘squashed’ penny.
But we like you anyway.
bean_shadow, you are a member of a very social organization; the one whose message board you’ve posted to here. I’ve certainly met some folks here.
Group hug for bean_shadow!