Having a smartphone loaded with MP3s is nice, but sometimes you want to listen to the radio. That's why Sirius XM radio has released an app for the iPhone that allows owners of any generation of iPhone to listen to their favorite Sirius channels. The app itself is free, but you'll have to pay for an Internet or Premium Online subscription in order to listen to anything.

Subscribers with iPhones or an iPod Touch will have 120 different stations to choose from. Want to start your morning off with some Grateful Dead before catching Opie & Anthony and then switching over to Oprah Radio for the drive to work? Now you can. Isn't technology geat?

In addition to keeping you connected to your favorite XM radio stations, the Sirius app has a couple of other nifty features. Hear a song you like while listening to the Hair Metal station? You can buy it on the spot from iTunes with the push of a button. Or, if you prefer, you can favorite it and flag it so you don't forget to buy it later. You can also favorite different channels so that you can quickly get back to the music you like most the next time you plug in your headphones and get ready for some tunes.

If XM radio sounds like something you're interested in, you can try it out by getting a free online pass. You'll get a couple of days of browsing time, and then the app will present you with the option to start subscribing. If you then decide you don't want to pay for radio and that all you need are podcasts and pirated songs, you can back out without paying a dime.