Heres a fun design for valentines combining woodwork, electronics and programming skills.
What can you do with a box full of spare leds some scrap wood and a soldering iron!
This is a 40+ led message with a charliplexed heart in the centre all behind a birdeye maple veneer and cherry case. Until its plugged in it just a nice polished wood case, plug in and the leds glow through the veneer.
Hardware is the brilliant shrimp arduino clone from www.shrimping.it, these have to be the cheapest easiest way to play with arduinos, add in a simple 9v circuit to give more power to the non arduio controlled leds and you have a really simple effect circuit.
Whats not simple is soldering the charliplexed heart, this has to be the most complicated cluster of wire I have ever soldered and definitely not for the faint hearted