Since I don't have anything pc related to post and the group seems kind of dead lately, I thought I would post what I ordered from Home Depot so I could play my iPhone through my car stereo. My car has a stereo with an old cassette player and needless to say it didn't have an external jack to play any other devices. This adapter from Home Depot worked great. Sounds 100% better than the FM stereo:
http://www.homedepot.com/p/iSound-Stereo-Cassette-Adapter-ISOUND-1642/207018846?