This was the first version. It has a itty bitty attiny10 driving it.  This was the first time I'd worked with an attiny10 and it was a good experiment.  It was driving  1 meter (50 LEDs) of SparkFun's sewable LED ribbon and with that battery, it was fading it in and out for about 24 hours on a single charge.

Pros

• Rugged (held up to over a week of use at Burning Man)
• Long battery life.
• Compact
• Charges from by USB

Cons

• Can only program it with an AVR ICE tool.
• Does not remember the last LED animation mode that was used. (attiny10 has no EEPROM).

Programming it via ISP with an AVR ICE was fine, but it wouldn't make it very easy to work on, if I wanted to make any last minute tweaks in the field. Also, we live in a time of USB bootloaders and I have some free time on my hands.