I used to think I needed long uninterrupted stretches of time to do good work. It turns out I was wrong. I'm working on a side-project now, putting in less than half an hour a day (but making sure to do it every day). Strangely enough I'm making better progress in many ways than when I had the luxury of spending many hours on side-projects.
I'm blogging on my progress, if anyone is interested: http://prehacked.com (read http://prehacked.com/pages/about-this-blog-53 to get an idea of what I'm working on).