At the end of 2007 I quit my job as the CTO of an online porn company, bought a new motorcycle, and rode south. I kept a pretty detailed blog:

http://www.advrider.com/forums/showthread.php?t=305107

It went great. I thought I would be gone six months but it ended up being just shy of a year. It gave me all the adventure I had hoped for and more - new friends, beautiful locations rarely seen by tourists, love affairs, very difficult situations, even a fair amount of genuine heart-pounding danger (jumping out of a moving cab at gunpoint; involuntarily evacuated from the Darién by the Panamanian army). I came back feeling tested and proven.

Yeah, I sound like a cliche. But it was really, really good for me.

To your questions: I started out with $100k in the bank. I didn't have a budget; I figured I would come back when I was either bored or felt poor enough. After a year I came back with about half that (including ~$14k on bike+gear, "fully depreciated" by the end of the trip). Honestly though, I burned money left and right; you could easily do the trip on 1/3rd that, especially if you're not an obsessive foodie. I didn't work on the road, other than pondering the question of "what to work on next".

Re-entry was fairly graceful. I spent all the rest of my money working on startup ideas that failed, but also building some opensource software that took off and eventually working that into a consulting business that at least pays the bills. I came back to SF expecting to enjoy a good long stretch as a heartbreaker but almost immediately began a torrid romance with a woman who is now my wife... so while nothing turned out like I expected, I count it as a success.

The trip didn't make me a fundamentally different person, but it did change me. When you can negotiate in broken Spanish to get your broken-down motorcycle pulled out of a goat trail in the rain with an ox-cart, most of the annoying hurdles that modern life throws at you feel pretty mild and tractable. Not much gets me worked up anymore.

My advice for novices considering extended world travel:

* Stick to the cheap but tourist-friendly parts. Latin America, Southeast Asia, India, Turkey.

* Travel by unusual modes. Motorcycle is great. Bicycle is better. On foot is even better. My wife and I spent two months walking the Camino de Santiago across Spain a year ago and it was the best trip of my life to date. The slower you go, the more people you meet and the more detail you get to see. Travel by bus or train is the worst - you can't even stop when you see something interesting. Although, amusingly, there's a contrary problem on foot - you have to make hard decisions about points of interest that are just a mile off track.

* Depth is better than breadth. Spend more time in fewer places. You can always take more trips.

* Take language lessons. It's a good way to spend a week somewhere and you'll often make friends.

* Do remote consulting, if you can. It not only brings money but gives you an excuse to stay in one place for stretches at a time. I wish I had my current contact network in 2008; I might still be out there.

* Assuming you are in technology and at least competent, don't worry about finding a job when you get back. Don't wait until your bank account is about to run dry, but also don't fret about it. Softwarewise, not that much really changes in a year. And when it does, it's usually not a good idea to be on the bleeding edge anyways.