They're fun when I have free time, but I haven't done any in years. I'm horrible at art trades, I never get around to them.
For people who are interested, I highly recommend finding websites that cater to specific types of art, places like Yahoo (and other non-art specific websites) tend to attract... not so great or reliable 'artists'. If you like anime art, find a group for that. Or animal art. Or collages. Or watercolors. Or cut-paper art. Or furry art. Or silverpoint. Or sifi art. Or monster art. Or surrealism. Whatever you like, you'll have WAY better luck finding someone that you really WANT to trade with if you find a style-specific site, and many artists who don't openly post ACEOs in their galleries may still be open to trade with you if you ask (and have examples of your work to show).