Hey Max, I don't think you're going to find anything really useful. If you take a look at what has been around for decades, the long wires work best. The quality of the antenna seems to far outweight the quality of the receiver for most case. I have a car with a $350 FM tuner that can't pull in stations my PoS Escort will with the factory radio. In fact, my Escort can get both AM and FM stations that none of my other cars or my home stereo can get (home stereo only uses 300-ohm dipole).
The headphone wires that constitute the FM antenna for iPods, Walkmans, etc., are really lousy, as anyone who has tried to use one can tell you. Forget about picking up a station in a metal/concrete building. The little stubby whip antennas built into headset with receiver built in are crappy too.
Sorry to be the bearer of bad news, but I don't think you can get there from here.