I just had a thought, none of us has ever tried to make a music game!!! That way it's still mostly a programming challenge.
OK here's my challenge:
You can use any music (you don't have to make it yourself) and you just have to make a game that is set to the music somehow, meaning it makes sure that you're listening. Think of DDR, Guitar Hero or the Bit-Trip series. Graphics aren't important for these challenges unless you want to make good graphics, your choice. (I know I will XD) If you can think of a unique way to set it to music go ahead and try it.
I'm honestly not sure how well I could make this work, because there's a few tricky details. But that's why it's a challenge right?
Tips: Use a program like Aquagnome (google it) to find the tempo of each song. iTunes may list it sometimes, I forget. I think I'd use a tick function to see how long the song has been running and keep the game synched. (In TNT it counts how long a song has been playing for you!)