[BIFL Request] FM Transmitter

I'm looking for a good, non-iPod-specific FM transmitter for use with an automobile. I realize that the superior solution would be to wire in directly, but unfortunately this is for my significant other's parent, and there is no chance that they are going to let me pull out their car stereo, despite my technical and electrical expertise.

Most FM transmitters are pretty shit. Due to FCC regulations, they almost have to be. That said, how can I get the most bang for my buck? Are there any small (or big) companies that make an FM transmitter that works adequately?

And no, the car does not have a tape player, so a tape adapter is not an option.