First, I put it in my spin-x to get as much water out as possible. A washing machine's spin cycle (top-load only) without water will do pretty well, too. I mainly have the spin-x because I do alot of fleeces -- there are over 20 in my basement right now (oh boy, I hope my husband doesn't read this blog!)
Then, I spread the fleece out as much as I can on a sweater drying rack (or three) and turn the heat up a little bit in a separate room. A small fan to help circulate the air helps too. The idea is to
get as much air circulating around the fleece as possible to help it dry out.
If you're in a very humid environment, a dehumidifier might help, too.
(based on a post by me on spindlers, 3/5/2007)