There's also evolved antennas.

http://en.wikipedia.org/wiki/Evolved_antenna

I remember reading this article a while back, and then some time later, reading another similar article, also about evolving circuits on FPGAs. (Note, by the way, that this article is only in theory evolving digital circuits: the run environment in this case is indeed analog, and the evolutionary algorithm exploited this in order to create circuits that had complex effects that would not be possible in a purely digital model!)

In the other case, the evolutionary algorithm found a long trace on the board that was to be an output from the FPGA (and so was undriven), and used it as an antenna to pick up the room's mains power and use it as a clock! I can't seem to find a reference to that one anymore, but if anyone else remembers this, I'd love to read about it again.

I remember reading this article in my High School's library a few weeks before graduation, all those years ago. It was what convinced me to major in CS. Even though it took me until last year to finally earn my BS, my very final project was inspired by that memory. I love when I see references to the article, or related work, because it is not only a reminder of my journey, but of how amazing the things we do are.