With all the posts for ATC swaps, if you are looking for more (can't imagine you are) I am a daily lurker at this yahoo group:
http://groups.yahoo.com/group/arttechniquesatcs/
It is a closed group and I don't know if they are taking sign-ups at this point but they are very very very very good! I entered an ATC Art Doll swap there a few years ago, and was stunned with the stuff I got back. Really professional stuff. So if you are looking to challenge yourself, or just lurk and learn, sign up. When you have to fill in a 'note to the administrator' tell them you're new and just want to lurk. Maybe they'll let you in. That's how I did it.
Sign up for the digest, they are quite active! I get at least 1 or 2 digests every day.
Attn 'advanced' ATC swappers or lurkers
Re: Attn 'advanced' ATC swappers or lurkers
Thanks for the info, I went over and signed up! Hopefully I'll get in!