Simple, inexpensive, compact, perfect. When we made the switch to a pedestal sink, we lost that bit of counter top for toothbrushes, floss, sunscreen, whatever. The stuff you don't really want to store away because you use it all the time, but don't want perched around the edges of your sink. Our solution was to install the Baren glass shelf ($9.99) from Ikea.
Easy to clean, it takes up almost no room (spacially or visually), yet holds all the things we want to keep close to the sink and mirror. Installed over five years ago, it has worked out great. Sometimes it's the little things that make a big difference... Available in store and online from Ikea. (Re-edited from a post originally published 03.14.07)