I just finished a project for my son's Chewbacca knit coat (it's a knit sweater that is supposed to look like Chewbacca from Star Wars). I used a lilypad protosnap board to work out all of the code with alot of help from TomS240 (Thanks!). I sewed the boards under the collar of the coat and when my son "pops" his collar, the light sensor picks up the light and starts playing the Star Wars theme from the piezzo buzzer.
Here is a really basic layout of how I wired this up. I was going to do it this way (turning pin 11 low to use as a ground), but when I started sewing, I got lazy and decided to turn pin A3 high and run the positive of the light sensor to that instead of sewing all the way around the board. I had already laid this out though, so I didn't feel like updating it, either way would work, the code would just have to reflect the A3 change.
After I had the diagram figured out, I sewed it to the under part of the collar on the sweater with conductive thread (like I said, I ended up sewing it a little differently than the above diagram).
Then I charged up the battery and had my son try it out.
It works great, and it was a fun project. More details about the code can be found at http://forum.arduino.cc/index.php?topic=227982.0
that has the actual code and all of the tips and advice from TomS240. make sure and scroll down far enough to see his better code since the stuff at the top was what I wrote before he helped me, and while it does work, not nearly as well as his code.