i just bought this Xtreme cooling towel from Groupon and it's fantastic to bring to gym. You wet it under faucet, wrIng it out, and it stays cool for hours. 20 degrees cooler actually. So not only can you wipe your sweat away with it you can keep it around your neck while exercising and it keeps you cool. Here's the link if it sounds interesting to anyone:
http://www.realxgear.com/product/real-x-gear-xtreme-cooling-towels/