I was looking for a FM radio transmitter and came across this article which explains the use of a raspberryPi to make a quite powerful radio transmitter. There are some commercially available short range FM transmitter for cars which has FM tuner. Also there are few long range one available which claims to have almost small city wide range ( of course it is not legally allowed to transmit strong FM signal without a license )
Last weekend I tried to follow the above article and succeed ! Also I used a micro USB cable as antenna connected to the 7th pin in the RaspberryPi. The signal was surprisingly strong, I could receive it in my neighbor's house also. I am sure I can make a better antenna.
TODO : I need to find a way to transmit streamed audio next.