Uncorked Events puts on professionally run wine tastings and seminars that are fun, with varying degrees of "seriousness".

The big tastings are a blast, they're almost always sold-out, and the people that show up clearly love their wine (but don't take it too seriously).

I enjoy the deeper wine-conversations, and having direct access to the distributors and/or producers is the main reason I go (since I'm married; if I were single, I'd go primarily to meet women!).