So when my youngest was born, I was reading up on keeping his teeth and gums healthy and it talked about washing them off with a washcloth before they go to bed each night. I do have a nice healthy stack of washcloths at my house, but that was just an addition to the loads and loads of laundry that I already do, so I didn't like that idea much, plus you don't need a whole washcloth for one little mouth!
Instead I hopped on over to the local dollar store and bought a bunch of washcloths and cut them into fourths. Using my mom's serger I sewed around the edges to keep them from fraying (you can use a really tight zig-zag stitch on a regular machine, or even just a straight stitch around the edge).
But now I don't just use them for smart dental hygiene! These little babies have a million uses and even though I only bought two or three packs of ten I seem to have an endless supply, so they last right up until I'm doing my regular load of dishtowels. I use them to wipe up small messes, instead of grabbing a paper towel, which saves me money and saves some trees as well. I have a dishwasher, so they work great to wash up a couple of non-stick pans.
To be truthful, it was probably the best idea I've ever had. :)