The radio-locator(formerly known as the MIT List of Radio Stations on the Internet) is your one-stop-shop for radio station information on the Internet. With links to over 10,000 radio station web pages and over 2500 audio streams from radio stations in the U.S. and around the world, why go anywhere else? radio-locator is truly a wealth of information.
There are a number of criteria you can search for (location, call letters, streaming radio, world radio) but one of their newer features lets you find unused frequencies on the FM dial. This is useful if you have a small FM transmitter (for your iPod or other portable music player, for example) and want to find the best (vacant) frequency to broadcast on.