I always bring a few of these along when traveling. Most hotels do not have enough places to hang a wet towel or bathing suit, especially if you are sharing a room with one or two other people. Just don't forget to take them home! I have found them in packs of 2 or more at home improvement stores and Bed, Bath and Beyond. There are several types on the market.
Another handy item to take traveling for the over 40 set (or just those with bad close vision) is a suction cup magnifying mirror. I put it on the mirror outside the bathroom so I can get close to it and can put on my make-up while my roommate is still using the bathroom.