You too can be a professional homeless bum! Check out these three websites to get you started:
www.housecarers.com - This website has the most extensive list of opportunities that I've seen. However, the website itself is hard to use.
www.mindmyhouse.com - Much better functionality, but fewer listings. This is the website where we got both of our jobs from.
www.trustedhousesitters.com - Brand new website, and it looks very easy to use, even though I have no experience with it yet.
I have been asked for this information so many times that I thought I should post it for all to see. Just don't go stealing our next job! =)