Dumping Old Documentation

I'm one of those people who hasn't been able to completely give up paper. Particularly when I'm dealing with reference material, I like having a book I can flip through, shove bookmarks in, or hold over my head while I lie back on the couch and read. It's hard to do any of those things with a laptop and a PDF. As a result, I've got a shelf behind me that's a veritable rainbow of O'Reilly titles and other technical references. But here's my problem... what to do with outdated editions?

I think I've got three or four copies of DNS & Bind, of varying editions, multiple versions of the bat book and some extras of C and Perl references. I'd like to try to find a way to reuse these before just dumping them in the weekly recycling. Surely someone out there might find these older editions useful for something..