Well, if you are on a budget I would recommend going with a Scion head unit (made by Pioneer) w/ ipod cable. They work with the factory steering wheel controls and wiring harnesses and require no dash kit for a very clean install. I bought one used with the ipod cable for $90 from another member on this forum. Installed it in my '05 Sport in about 20 minutes.
The only drawback is that I had to get a small adapter to allow the unit to charge my iphone. I tucked the adapter under the center console though and ran a dock extender cable up and out, so you could never tell that it's there. Works well, sounds waay better than stock, and was a breeze to install.
A friend of mine has a touch-screen pioneer nav unit in his Tundra (AVIC X920BT I believe). It works well with the iphone and has bluetooth, satellite radio, and dvd-playback capabilities. Very nice unit. If I had the $$ I would have gone with this for sure.