Cool little project. Might be interesting to try to make a circuit that could broadcast actual noise on multiple frequencies within a certain distance. That way, it could play to multiple stations on a radio it was next to. :D
Not sure how legal it would be though...probably not at all...
Such a circuit would want a transistor and not a relay :) I hope to build some more transmitters in the future and get to the point where they are actually useful.
And hopefully look a bit better. :P