I haven't seen a group trade here on the forums in quite a while, who would be up for one?
Personally, I've always liked the simple swaps that used to take place, draw names randomly to pair up partners and those 2 decide what they are going to trade. I've always had fun doing them and have gotten to interact with someone just because we were paired up as trading partners.
The only rule I'd suggest is that you need at least 100 posts to join. I'll randomly draw names on July 29th. Just say "I'm in" and put the next corresponding number in front of your name, I'll be #1.