I recently purchased my own microfiber towel to carry around with me at the gym to wipe my body. I am in love with my new little towel because it's way softer than the ones provided at the gym, and I know where it's been.
This Aquis Adventure Small Microfiber Towel ($8.69) is lightweight and compact; making it ideal to stuff in your gym bag. Since it's microfiber, it also dries quickly between uses, avoiding any potential mildew smells. Buy it here.