I have no idea how many books I have in my house...not counting the kids' books (of which, there are probably thousands, all missing pages and colored on) I have probably 20 or 30 (not counting geek books, of which I have at least 100), but then I know there are at least 4-5 big boxes of books in storage, which hold about 20 boxes, so thats like, 100 or something.
Then again, I also have a 40 gig hard drive dedicated to e-books, of which most are really boring things that are not interesting unless you are a total project geek like me. So each book on the ebook list is probalby 5-10 mb, and the hard drive is pretty full, so that like, a bijillion.
Most of those are on economics, international economics, communications technology, marketing, business management, project management, risk management, portfolio management...the list goes on and on. Then there are the ones I have no use for in my job but they are fun anyways, like physics and chemistry, string theory, ect---not that I understand them, I just really dig the pictures.