When the back of my sink began looking like a mess of cleaning tools, I couldn't stand it anymore. With a dollar store gallon bag and three binder clips, I made a little "out of sight" place they can be handy. If you don't have the towel rack, you can still do this with three cup hooks to hang the clips on.
NOTE: If you can, double the bag or use a really thick version like Ziploc. It will hold up better.
