Woodworking/Carpentry. As much as I like writing code and working in Product, it'd be nice to work on something tangible. It's so much easier to give someone a physical product that (for the most part) is 'done' when it's handed over, and there's also the knowledge base that remains mostly intact and isn't continuously iterated like it does in programming.
It's cool watching someone I knew at uni build something that's useful for so many people, especially seeing him pop up on Hacker News from time to time!