My old high school friend (who wishes to be called Blind Lightnin' Pete), built the electric cigar box guitar in Make 04. He also built a tiny batter- powered amplifier inside a cracker box for $(removed) (He mailed one to me, and it's beautiful).
Blind Lightnin' Pete is writing an article for Make on how to make one of these amps.
Here is a video of BLP playing "Out of Milk and Butter Blues" on his cigar box guitar and cracker box amp.
Link