Pandora is a neat tool. It creates a personal radio station for you based on the musical style of an artist of your choosing. You can then customize it further with feedback on individual songs it has chosen. I'd like it to do more to expand my musical interests rather than just continually focusing or shifting them. And I'd also like to see it incorporate non-label music. But as is, it's a great example of where radio is headed.
Here's my plan for a useful Google maps tool: take the FCC's database of radio station information (e.g. stations in Des Moines), and figure the span of each station (like so) to provide a tool that allows people to click a location on a Google map, and get a list of radio stations and signal strengths for that location. Bonus points: 1) Search Google for each station's website, 2) Search each website for an online version of the station's audio, 3) Provide an interface for listening to each station.
Now, who wants to make it?