I use the Belkin Tunecast universal:
http://www.thesource.ca/estore/Produ...710AF89ADF0885
It doesn’t charge the iPod, but I like that its a universal plug - I can use it with other devices if needed. Beware of any transmitter that relies on or includes software on the iPod itself (eg. anything that displays info on the iPod screen) - these tend not to be compatible with new iPod models as they come out, which is a royal pain in the *ss and a waste of money if you tend to upgrade your devices.
I find the reception on this one is pretty good - you have to figure out what volume level to set the iPod at for best sound (too low, and there is background hiss because the signal to noise ration is too low, too high, and it clips and distorts), but that’s easy and easy to remember. On my iPad, for example, its happiest with the volume at the 3/4’s mark.