Step 1: Parts:
1 Bluetooth headset and charger (can be had for about $10 at your local electronics store. I used an old Jabra headset, but anything will do)
2 LEDs. I recommend blue, but any color will work (For the indicator lights)
2 resistors (see note)
1 Screaming Monkey Slingshot (http://www.thinkgeek.com/geektoys/warfare/8f00/)
Diagonal Cutters or Wire Strippers
Hot glue and a Hot Glue Gun
The resistors here will vary. My headset's power brick outputted 5v, and LEDs can take 2-3v. As such, I used 2 1kohm resistors to make my voltage divider. To find which resistors you need, use ones in the ballpark of 1kohm, but adjust them so r1/r2 * (Total voltage) is somewhere between 3 and 4 volts.