I have one of these.
http://www.macally.com/EN/Product/Ar...p?ArticleID=35
My only complaint about it was that it didn't come with the dock insert for a second gen Nano, but the apple one the nano came with just clicks right in. Apparently they've fixed this since. Reception is as good as FM can get.
Honestly, if I was doing it again, I'd get a new stereo with an ipod input.