M.S. Living had an interesting "good thing" regarding towels. If you find your towel is starting to not be as absorbent, it could be because the detergent you're using has fabric softener. Apparently, fabric softeners have "residues that cling to individual fibers, rendering towels less absorbent." The recommended solution is to use a cup of distilled white wine vinegar to your rinse cycle, which will remove the residue.
Chalk up another one for the ever useful vinegar!