I just did the same exercise in my house. I picked up a circuot tester
at Home Depot. It only works with outlets, but it works great. You plug
a device into the outlet you want to identify. Then you go to the
breaker panel and run a wand down the circuits. When you hit the right
one, it the wand starts beeping. This is SO much better than the old
way! Saved hours, and did a much more thorough job. My old house had a
number of funky wiring combinations (never knew the master bath was on
the same cicuit as the garage lights) that would have taken a while to
figure out without this device.

They have also updated it since I bought mine to make it easier to use.
Here's the link:
http://www.homedepot.com/prel80/HDUS...l.0& MID=9876