I'm the archivist for the free Graphics Gems code base on the web. I do it for free, because this code is so valuable. Others think so, too: there is an average of 100 hits a day on the site. Go look at the online list of what's in this volume to see if it's for you.
Highlights (for me) include polygon/cube intersection testing, a good polygon triangulator, and an entire z-buffering library.