I may be slow, but I just discovered Google Books yesterday. Big list of books, a place to find out-of-print books available online, descriptions, etc. Still gotta look into it further. Good for writing research, finding books to read in my genre or whatever. To see what else is out there, especially to compare and see how a particular book I'm writing is like others out there. Ya know, type in a subject and see what pops up, and if it's similar.