One of the things we ask in our interview process here at Effective UI is whether or not you're involved in any extra-curricular activities (having a family certain counts.) Regardless of what those are, it shows us you're probably forced to keep a healthy perspective on work when you're doing other things as well.
Another good characteristic of people who live outside of work that DHH didn't mention is that they know how to commit. If you're committed to volunteering or playing soccer or doing anything that requires regularly sacrificing your time, it's more likely that you'll commit to our company and be a more enjoyable person to work with. Being committed means you're more likely to enjoy your time with us, more likely to get involved in fixing company processes, and more likely to care about what happens to the rest of us. No one concerned with company culture wants to hire a mercenary.