I participate in a couple of ATC swaps. One with my GOE fibre art group and one with Lisa Fulmer at http://lisalizalou.blogspot.com/p/atc-swap.html. Check it out if you'd like to participate.
Lisa sets a theme each month, so I always make 3 ATCs at a time. One I keep for myself, and the other two are used for the swaps. This month's theme is Earth Day. I had been playing with some wet felting and needle felting (using my embellisher) and I made a nice mix of green, white and blue swirls that reminded me of some of the satellite shots that we sometimes see of the Earth. I like the texture and depth that the Earth has to it.