I have previously bemoaned that I had not seen many (ok, any) Arduino Leonardo projects. I have a saying that if you see something once it is cool, if you see it twice, it's a trend. Via my post on the Raspberry Pi AlaMode board, I saw a post from those folks on an FM radio interfaced with Arduino. Well tonight I browsed Club Jameco (sad but true) and saw an idea for a sound localization board for Arduino (cool!) and the author is the same as the FM radio author.
Magiciant writes the coolarduino blog. He's doing some signal processing on Arduinos that is very interesting. My favorite is a sound localization add-on (above) using 4 electret microphones for x and y axis tracking. Another is a speech recognition project. These are things I was investigating with the Raspberry Pi. Just coincidentally, Adafruit has come out with both a very good electret mic and a mic+amplifier.
Finally, to get better capability, magiciant has migrated his initial designs to the Leonardo, apparently due to input sensitivity and a couple other factors.
This may move my robotic head project forward - I have the head and servos, now to have them do interesting things.