I was reminded by Slashdot of the DIY Book Scanner (complete HowTo (PDF)) designed by Dan Reetz (who also has another interesting blog about the future of photography). He got a nice writeup in Wired recently, which was what prompted the Slashdot post.
The project seems to have adopted (and spawned) a bunch of interesting technology, including some Free Software such as StereoData Maker (Canon hack for synchronised shutter releas) and Scan Tailor (deskew and page splitting) for dealing with the paired shots of the book pages.
I've been trying to figure out what to do with my old camera (Sony DSC-P1) now that it's been overtaken by newer models. But unfortunately being Sony rather than Canon, it's much less hackable. I suspect any reuse would require some sort of mechanical button press mechanism.
Dan Reetz seems to have done a bunch of other cool stuff, including a Steampunk Kindle design (which won an Engadget design competition).
(See also earlier Ask Slashdot which referenced this, and other solutions. And the Book Liberator and related site: Question Copyright.)