Dancing is good advice because you have a good mix of genders and it's something you can grow to love over time. It's also a great community that's fairly welcoming once you start going regularly. Take a class and you automatically have a social group of other beginners.

The problem with nerds finding a social scene for what they already enjoy doing already is that there's a very good chance it's going to be a male-dominated activity. Going to a tech meetup or a board game night is a decent way to make friends, but not so much a mate.