Well, it's done! Here's my ATtiny13 controlled Christmas LED hat. It consists of an 8 pin, ATtiny13 microcontroller, a pair of 2N3904 transistors and some 1K resistors, a 7805 voltage regulator with two filter caps, and a switch, all mounted on a Radio Shack perfboard inside an Altoids tin. I'm rather pleased with the way it turned out. I always like it when a project goes from the breadboard to a final mounting in a box.
Addendum: Here's the schematic for the entire circuit. Nothing too surprising, but you should be able to follow it if you need to.