Not sure if this is the right place for it, but since it's kind of a display, I'd post it here.
I just finished my first RPi project--A Binary Clock. I had purchased a bag of random LEDs a long time ago, and one of them was a 5x8 LED array. I'm using that array as the output for a binary clock.
Here's a video of the clock in action.
Of course this isn't the "end use" of my RPi, but it was fun, and I learned a lot about it already.