I hire a lot of people, so I see a lot of resumes. My opinion on interests and hobbies is that you're making a statement by including it, so you need to be smart about it. If they're mundane and not salient to the job, then you're padding a thin resume, or just being dense by including them.

On the other hand, they have the ability to make you stand out or advance your "story" then they can make a big difference. For example, if I'm hiring an engineer, and they mention that they've been working on an interesting open source project, or they co-founded a local hackerspace, then that's a mark in their favor. I hired an intern, who I later hired on full-time, largely because he described a scrappy and interesting local entertainment directory website he had been working on launching. He'd been basically living as a ski bum for three years and working as a waiter, but his ambitious hobby made up for that.

This wasn't on his resume, but a another guy I hired recently let me know in the interview that he plays hockey seriously, and that was good to know, because honestly some engineers need to get out of the house more.