SiriusXM XM SkyDock In-Vehicle Satellite Radio for iPod /iPhone with PowerConnect
Just keep this in mind: the SkyDock does NOT work with iPhone4!  It does work with the previous gen iPhone.  Another baddy about the SkyDock is that ANY bridge you go under will knock out the signal!  There is absolutely NO buffer whatsoever built into this thing!  Buy something else, unless you're using an iPhone or iPod that's compatible with this thing--in which case it is a very nice item to have.