Not to be negative or anything, but I've never understood the appeal of ATCs (Artist Trading Cards) or the related ACEO (Art Card, Editions and Originals) They're 2.5" by 3.5" cards made of whatever you like, decorated however you like. I guess the idea is to make something that shows "what you can do", artistically speaking. Fellow artists trade them to admire one another's work-- maybe even get inspiration for ways to improve their own creations.
According to the wiki on the subject, they haven't been around for all that long-- only since 1997. (1997 happens to be a landmark year for me, since it's the year I graduated from high school.) Since then, they've gained popularity among artists in a variety of media, including polymer clay.
If you're just trading them, ok. It's probably fun to be in on the trade, and I suppose you can display them as miniature works of art. Kind of like the original sports trading cards (though I never "got" those, either, not being the sporty sort).
But these days, I've been seeing them for sale, and I really don't understand that. Maybe it's different for people who aren't interested in jewelry, but I'd much rather have a bead or a pendant that I can wear or at least make into jewelry for someone else than a little rectangle of clay, however prettily it's been decorated.
Maybe my reaction to ACEOs is the result of my frugal nature in combination with my jewelry-making tendencies. What?! Make something out of clay that can't be worked into jewelry and worn?! What a waste of good clay! ;o)
Well, even if I'm still rather mystified by them, it's obvious that many others are not-- and I can appreciate the skill and work that goes into many of them. For instance, PCC hosts photos from a couple of ATC swaps: Here and here.
(If you enjoy those pages, check out PCC's swap index for more photos from polymer clay swaps.)