I picked up a bunch of momentary NO (normally open) push button switches, a couple of mini breadboards, and some jumper wires from sparkfun.com
They sell male-female jumper wires that fit the motherboard header perfectly, and plug right into the breadboard. 10 seconds later and I've got a 'real' power switch
It's not the cheapest solution, and these parts can probably be found cheaper elsewhere, but I had picked up all this stuff for another project. The jumper wire is perfect for quick prototyping.
Wires:
http://www.sparkfun.com/products/9385Switch:
http://www.sparkfun.com/products/97Breadboard:
http://www.sparkfun.com/products/7916These guys are more or less in my backyard so I didn't have to pay shipping either, which saved a bit.
If I remember I'll grab a pic of the switch when I get home.