I'd like to create something that activates based on a "clap clap" sound. Is anyone aware of something like this? Some kind of condenser microphone combined with a pattern recognition library maybe? At first blush it sounds like too much for the Arduino to do, but maybe it's out there? I wonder how the real clapper does this.
I don't know about pattern recognition, but have you seen this? Perhaps something like that could be useful to you.
I do have one of those. I didn't think I could use it for a clapper, but now that I think about it, maybe I just need to look for an analog value of X, then within 1 second, look for another value of X? But I could imagine that happens so often during the normal stuff that happens during the day...it would be nice to be able to refine it a bit
Old school way...
Or feed the amplified signal into a0 of arduino, and then switch it on (lot easier too) but I like the 4017 
That's neat, but I will be using an Arduino. The output is going to be an IR signal coming from an Arduino, so I might as well hook up the microphone input to the same Arduino.
The trick is trying to sense when there is two claps and reject other non-clamp signals, including TV noise.