A perfect project for the fans of Minecraft is this binary clock with a 3D-printed housing. Designed to resemble an object made during the game, the clock is filled with LEDs to allow the display of time in binary fashion. Although building your own binary clock isn't the most original idea - the housing for this one is. And if you don't have a 3D printer - use LEGO instead!
The designers of the Minecraft clock used an external Arduino board, however to make a completed clock consider embedding the Freetronics LeoStick. Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo for an alarm clock, and it's own form of knock detection to use as a snooze button: