After watching a friend demonstrate how a Raspberry PI GPIO pin could be used to transmit an FM signal for a short distance, I wondered if the same could be done with an FPGA GPIO pin. This project is that attempt. This transmitter is by no means "approved" by the FCC or any other regulating body, so please only use it in a lawful manner. (My hardware transmits a signal that can only be heard within a couple inches of the receiver.)
You'll find the core in the rtl/ directory. I finally had the guts to test it this morning (14 June, 2016). It works!!
The only caveat was that I needed to strap together multiple GPIO I/O outputs to the output of this device, and even then it didn't transmit for more than a couple of inches, still ... that was enough to prove that the concept works.