COOL WEB STUFF
There's a couple places to get free books:
Project Gutenberg (NOT www projectgutenberg org): This is the old standby and the first real successful archive place. The quality is high. The only downside is that it's all text. Therefore, diagrams are missing.
Google Book: This is the new one. It is really nice, except I can't browse. Graphical intensive. The search engine is decent, but I wish it'd be set up like a library so I can browse similar subject books. I know that it's not set up that way, but Amazon does have something like that.