If one is more interested in "mail art calls", by the way, those requests for mail art on a particular theme, for use in a "mail art show', then one might check out www.crosses.net, where the forums include a message board for mail art calls. Mail art involves no awards, no returns of what you send, no juries, few "rules", no hassle, but documentation of the event is generally sent to "all" who participate.
One mail art call really interests me right now. It's a request for chess sets for a show in Europe. I wish to participate, but I'm trying to think how to make a chess set without any particular arts and crafts skills. I have some good ideas, but I wonder who might suggest ways for an artless person to make an art-oriented chess set?