Keep one in the shower filled with a mixture of half vinegar and half Dawn dishsoap. Use it to wipe down the shower while you are in there and your shower will always be clean. I keep hearing that this is the magic formula!
Recharge your towels! Run them through laundry twice - skip detergent both loads. First load: hot water + a cup of vinegar. Second load: hot water + 1/2 cup baking soda. Towels are fresh and absorbent.