If any of them are out of copyright, the internet archive (www.archive.org) might want to scan them to put them online. There are lots of other scanned math books on the site right now. I really love this one even though I can't read any of it: http://www.archive.org/details/rieflachvolesung00klierich
The book is handwritten text (in German) of lectures about Riemann surfaces by Felix Klein and it's just wonderful to flip through it on the screen.
