Canon compacts with DIGIC II or III processors have more capabilities than appear on their menus. Functions such as high-speed shutter and RAW mode can be unlocked using firmware available via the CHDK project (Canon Hacker's Development Kit). WIRED Magazine helped shine a light on this work with their recent article, Supercharge Your Camera with Open-Source CHDK Firmware. It's a terrific overview piece with lots of links, and I suggest you start there if interested in this project.
I have a Canon SD700 IS that I'm going hack. It's a wonderful little camera that I use primarily for underwater because I have a matching housing for it. I want to be able to capture in RAW while snorkeling, and CDDK seems like the way to go.
Of course, anyone trying this does so at their own risk. But if you've tested CHDK, please post a comment and let us know how it went. And if you're interested in trying it, here's a list of cameras.