I made a great zippered wetbag today for my wet swim gear and/or sweaty gym clothes. I used 1/2 yard of cotton (found on clearance for $3/yd) and lined it with the very awesome PUL. It's super roomy without being bulky.
I just keep it in my gym bag. Much cuter than the Gap plastic shopping bag I've been using. I'm lovin' it! :)