A few years ago, I spent a year touring the continent on a bicycle, by myself. As you might imagine, I spent many hours listening to the radio. Bringing my music collection along was out of the question for space reasons -- the iPod and other MP3 players were still relatively new and expensive, so I hadn't bought one before the trip. Satellite radio, same deal. So when road noise threatened to drive me bonkers, I turned to the FM band. And you know, there's just not a whole lot of variety out there. With a few exceptions in big cities and quirky places like Louisiana or Canada, you've pretty much got the same stations everywhere you go.
I remember fantasizing about an iPod that would automatically download music whenever it was in wi-fi range. Each time it played a song, you'd have an opportunity to indicate whether you liked it or not -- if so, it would buy the song for you to listen to again later; if not, it would never play it again; if you didn't vote either way, the song would be deleted after playing for copyright reasons. Over time, it would get to know your musical taste better than you did, and it would expose you to artists you never would have heard on the radio.
I'm not saying I invented Pandora or beat the inventors to the idea -- they were probably already working on it before I got the idea -- I was just tuned into the zeitgeist. In any case, that's pretty much what Pandora is: your own personal radio station, with a few differences.
It doesn't download music to play later, so you have to be in wi-fi range (for an iPod Touch) or digital reception range (for an iPhone) when it's time for the next song. So it might not work for a bike tourist, but for listening at your desk while you work, it's hard to beat.
Rather than starting with a random selection of songs, you start a "station" by naming a song or artist you like, and it finds other songs that it thinks are similar. Sometimes it is dead wrong -- I entered "God Bless the Broken Road" and got nothing but Christian tunes, for example; and entering "Weird Al" Yankovic will net you a lot of stuff with explicit lyrics -- and its index is missing a lot of the small-name, small-label artists that I had hoped such a business model would give exposure to. But on the whole it does a good job, especially if your tastes are more mainstream. While a song is playing, you can amuse yourself by reading Pandora's explanation of "Why this song is playing," which may or may not bear any relation to what you had in mind when you created the station.
Giving a song the thumbs-up doesn't buy it, you have to go to iTunes and do that, and your iTunes library is separate from what Pandora plays, so buying a song doesn't make it more likely to play on your Pandora station. But you do have some control over whether you're voting for the song or the artist. You can't vote against an artist, as far I as I can tell, just give him or her a repeated thumbs-down.
A feature I didn't anticipate is the very pretty cover art that accompanies most of the songs. Pretty, that is, unless it's not. Since you have no control over what comes up next, you might want to keep your screen hidden lest an onlooker get the wrong idea about your taste in artwork! I guess that's why it's called Pandora.
Did I mention this program is absolutely free, paid by very discrete ads that don't interrupt the music? Unlimited music without commercials -- better than satellite radio, and free of charge! Enjoy!