Last week I finally bought a 'digital clamp multimeter - item 42396'.

I rushed home and clamped it around the power cord of the computer
that I leave on all the time. I wanted to know how many amps it was
drawing or how much money I'm wasting by not shutting it down. It
read zero of course, as I guess you need to hook it around one side of
the line at a time, right?

YOu need to clamp the meter around only one wire in the cable. Make sure it
is not the ground wire either. There should be no current on the normally
green ground wire. If it is you have major wiring problems.
You may want to make up something like a short (about a foot long) dropcord
with 3 seperate wires to make the measuring easy.