i made a fuzz pedal for my bass, its a whole lotta fun 
it wasnt too hard either, fairy simple schematic but i put the transistors in the wrong way round i think and had to get my physics teacher to sort it out
all the bits cost me about £20 which is cheaper than a real one but i had to settle for a crappy switch cos they is damned pricey! when i ordered the bits i got a wee kit of 10 flashing leds that i put into the front, but there wasnt room in the box for the board and wires so i taped it onto the outside with black tape! sprayed it yellow and threw on a few snoopy stickers!
if i hook it up through my chorus pedal i can get weird fedback that sounds like running water 
theres some piccies of it here:
http://mudlarks.members.easyspace.com/neil’s%20fuzz%20pedal.htm”>http://mudlarks.members.easyspace.com/n … 0pedal.htm