I just came back from a 9 month break.
After being in the Valley since the dot-com boom, and going through the bust, and other personal issues, I was pretty burnt out, suffering from stress-related health issues, and after a couple of health scares, decided enough was enough.
I quit my job amicably, and spent 2012 just "doing my own thing". This entailed spending time on small, frivolous projects that I normally wouldn't have had time to pursue, and learning things that might help me in my career later on. I also spent a lot of time cooking dinner for my wife.
I don't spend a lot of money in general, but even so, I didn't curtail my spending at all, so I ate through a big chunk of my savings. I didn't care, and my wife and I even went on several trips. Obviously, having a working spouse helps, but one thing you learn after suffering through a few health scares is that money will come and go, but you're only young once, and your health (physical and mental) is pretty much the most important thing you have.
I didn't have any vast goals like creating a startup, or even creating my own iPhone app. I ended up not doing a lot except learn, but I really did feel refreshed and more important, I felt a lot better about myself and about programming in general. I spent 6-7 days a week, 6-10 hrs a day programming and learning, so I didn't waste any time at all, but didn't feel stressed out once. I even started working out again, although I didn't hit any of my weight targets.
After about 9 months, I figured it was time to get back to the world of the gainfully employed. Thankfully, no one cared that I took the time off, and I was able to get a new job at a company that I really am excited about within a few weeks.