Ask HN: What should I work on?

I'm a college student with some free time and I'd like to build something. Frankly I currently have no idea what to work on. I'm happy to learn any new technology. Mostly I'm interested in deep learning/neural networks and recently I started learning web development. It's particularly fun to combine technologies - like deep learning and some app or website. Anyone willing to share their tips/ideas on what to work on?