Xander Hudson, aka Synoptic Labs, posted this cool heart card project to the MAKE Flickr pool. He writes:

This year I gave my sweetheart a LED valentines day card. The LEDs were animated with a pulse harmonic tuned to my own heartbeat. (sappy, yeah I know, but she makes me feel sappy). Incorporates 1 AVR ATTiny45 microcontroller driving 2 constant-current shift registers driving 16 LEDs.

Bill of Materials:
1 AVR ATTiny45 microcontroller
2 STP08DP05TTR 8-bit contsant current shift registers
16 red LED’s (0805 package)
Pyralux flexible circuit board material

Synoptic Labs

LED Valentine’s Day heart