Crazy High Tech Solutions pale in comparison to old - school ones. Divide your book cases up Fiction and Non and categorize from there. Put the books most commonly read on easy to reach shelves. My parents have easily that many and don't run into any problems looking for the book they want to read. It is enough to have a vague idea of where the book is, History of Computing - Non Fiction around shelf 3 and call it a day. How do people find books at a bookstore anyhow?