My wife's mom had over 30,000 books.
Not a misprint, she had over 30,000 romance books.
She had boxes of books in storage, stacked to the ceiling, it was amazing. Every couple days, she would go out and buy another romance book and read it, and this had been happening for decades.
We bought them a computer, I got a CueCat barcode scanner (and modified it to output proper barcode), then I wrote a program for her. She would run the program, then run the barcode scanner over the barcode for the ISBN(for the books that HAD them, many were THAT old). The program would ask Amazon if it knew the ISBN (95% of the time it did) and then the program would download the title, author, # of pages, genre, etc from Amazon and put it into an Access database.
It was a real timesaver. Her plan was to sell them on eBay, but there's such a glut of romance novels on eBay, that it wasn't economical even with the automation doing the work.