I guess I'm reviving an old thread, but I had to put in my recommendation.
My hair has been thinning for awhile, and I don't like to leave the top uncovered. I've started using the situation as an excuse to experiment with making hats for myself. I have a whole pile of caps that I've knitted and crocheted in different colors and patterns, and have had a lot of fun wearing them. I love how my hair looks out the bottom of a hat- you could never tell it's thinning out!