I use Meetup.com, and used to go to quite a few Asperger/autism spectrum events from there. Unfortunately, I didn't find most of them to my liking, as they consisted of people just sitting around and talking about AS. There was little sharing of special interests, playing games, etc. It might have something to do with the fact that these groups had a huge age range, and had many people who weren't diagnosed until adulthood, which means that they never developed their own "aspie culture" so to speak.
My best match has been a young adults group for people on the spectrum that does fun activities. However, it meets less than once a month, and so I haven't had the level of contact with the other members necessary to really form friendships.
What did you want to know about using Meetup to find others on the spectrum?