I read an article today on Hack-A-Day, about a guy who created an 'electronic' business card. The electronics part of the card make up the game 'SIMON'. You know the game - the game flashes colors and your have to press the corresponding buttons.
Anyway, I didn't like his circuit - he was using a ladder network for the switches - so I re-designed the circuit and managed to get 4 LEDs, 5 buttons, and even a piezo speaker for the beeps and buzzes.
I haven't prototyped it yet, or done any firmware work, but I really like the way the card looks *grin*. I like dark green solder mask, and it looks darker when it's covering traces, so I took advantage of that fact. And I when with white silkscreen for the actual 'business card' part.