Students interested in one day becoming founders may enjoy the software design contest. I did this contest when I was a freshman in college, and I loved it.

My friend and I decided to register about 5 days before the competition. In those 5 days, we came up with a business idea, designed the application (which consisted of a server, a web ui, and a desktop application), coded it up, and prepared our presentation.

Great practice for a YC interview IMO. You come up with an idea, demo it, and convince a panel how awesome it is.