There are more than 6000 questions on this website and they're all free but if you want that kind of trivia power without having to turn on your PC or without having to trust your broadband connection to keep functioning, you might fancy getting it all in a book.
Quiz Master by Nick Holt claims to contain 5000 trivia questions in one volume. From my own personal experience of putting this site together, I can tell you: that is a bunch of questions.
I haven't seen it myself but the reviews on Amazon are decent enough, although one reviewer complains that the questions are too hard for the elderly. I guess you can't have everything.