I have a Canon SD800is camera, I bought that one and the SD600is about four years ago. I take this camera everywhere with me and I have dinged it up many times. It is a workhorse and I am happy with the results I get from it. About a year ago I learned about this CHDK (Canon Hacker’s Development Kit) from Lifehacker and I installed the Canon Hacker’s Development Kit onto one of my SD cards (I accidentally formatted the thing a while back and never reinstalled it but will soon) so that I could shoot some time lapse stuff. I wanted to be able to set it and forget it when I took a bike ride. The closest I came was a Shopping cart and a Stroller ride with my daughter.
The Canon Hacker’s Development Kit is a piece of code that you can install on your SD card to be able to run all sorts of scripts that enhance and extend the capabilities of regular old point and shoot Canon cameras. The time lapse script is called the Ultra Intervalometer and with it you can set the rate at which your camera takes pictures. So if you wanted to have the camera take photos every 10 seconds as you rode your bike around your town you could do that with the CHDK.
That is just one of the scripts that have been created to automate and unlock special features of your camera. Some other features of the CHDK are enhanced image capture. You can actually capture RAW images on a point and shoot. You can set longer exposure times, you can even see more info like remaining battery life, histogram, depth of focus. The Lifehacker article and the CHDK wiki are great information sources for you to hack your Canon as well. If you do it let me know and share your experiments in the comments below.