Sky Dock allows users to get Sirius XM Radio signal on their iPods or iPhones.

Ever wanted to listen to Sirius XM Satellite Radio in your car but was discouraged by the cost of paying for a new one? Now you have a more flexible option thanks to the iPhone. We know that the iPhone can do a lot of things by way of the multitude of Apps that are added every day, but in this case, some extra help is needed in the form of a separate device called Sky Dock. To get it to work, you place your iPhone or iPod onto the Sky Dock which in turn is plugged into the car's cigarette lighter power port.The built-in antenna pull in the satellite signal and a FM transmitter beams the music or whatever you are listening to, to your car stereo system allowing the signal to go through the speakers. The connection is straightforward, and once it is done, the next step is to download a free app from the iTunes store. The App will allow to control the XM turner using the iPod or iPhone screen interface while the Sky Dock keep them charged.
Beside just listening to their favorite programs, users can tag songs for later purchase at the iTunes store, play games, receive all sort of alerts or follow different tickers.
Access to XM Sirius Radio content is not free, with the subscription costing $13 a month. The device itself retails for $120, but some sites like Myradiostore.com and Amazon.com are offering it on sale for $96.99 and $101.45 respectively.

For more, see the NYTimes.com