I've seen tons of posts about converting FM signals to AM signals
(say, to use with an AM only vintage car radio). But I haven't seen
anything about the inverse: converting an AM signal to an FM signal
(because there are quite a few FM-only devices on the market now, such
as MP3 players). I found this: http://www.uashem.com/pageid-259.html ,
but it doesn't really fit my criteria. I'd like to be able to tune in
any AM station, and then select the frequency to output it to without
interfering with other station (think iPod transmitter).

Surely there's gotta be some out there...