You could also get an adapter that works using your cars stock stereo to control the ipod functions. I bought one for around $70 I think, and it comes with some harnesses specific for your car and a long ipod cable, the one that goes into the bottom to charge it.
Installation was fairly simple it was plug and play. You basically unplug the factory harness from the radio and plug it into a box that comes with the kit, then you plug the harness from the box into the stock stereo. Then the ipod/iphone cable comes off the box and you can run it to where ever you want, I have mine in the glove box.
To use it, I hit the AUX button on my car radio 3 times and now there is a 4th option that shows on the display for ipod. After this you can play and scroll through all your music. Works pretty well so far. And if you get an incoming call it will pause and ring through the car speakers as well. Only part that is a bit of a pain is if it rings while your driving, unplugging it to answer.
This setup also gives you another option for AUX 2, so for instance that box has another input on it, which I plugged my sirius radio into so that comes through the speakers as well.
I am pretty sure this is the one I had bought, but its clearly more than I thought I paid. Maybe it was on sale or something at the time.
http://www.bestbuy.com/site/olspage.jsp?skuId=8760888&type=product&id=1202650491 628