So what are some good online resources for finding gay support groups nationwide?

Gcursor

IMHO, if you are in LA, NYC or SF the first place of contact is the local Gay and Lesbian Community Center. I did that in NYC when I first came out and joined a group called the 20something's. I had a great deal of fun and met a lot of great guys. I also joined a few other groups and had fun with the entire community center for several years.

I think I met some of my best friends at God's Love We Deliver, a group that cooks and distributes food to shut ins with HIV. I'd spend all day peeling carrots and laughing with the coolest group of cats in NYC.