I just scanned a couple books this weekend and wish I would have read this thread first. Lot's of good information, and I think I've been sold on ABBYY.
Here is what doesn't work: Scanning each page with a cheap scanner and then printing the images to PDF, followed by using the PDF's software for OCR conversion.
Actually, I think my biggest problem was not the OCR conversion, but was poor scanning that resulted in poor OCR conversion. I was using a flatbed scanner and anywhere that the page wasn't laying flat resulted in tons of OCR errors.
In my case, I'm scanning old books that I don't want to destroy. This means cutting off the binding and using a flatbed scanner is out of the question. I don't even want to press real hard on the book to get it to lie flat, because I'm afraid I will break the binding and have my pages falling out.
I looked at the DIY book scanner projects, but most of them looked like a huge amount of work, and I'm not so sure I have the room for the resulting scanner. However, one set of instructions I found for a
cheap scanner looked promising. I suppose I'll give something like this a shot and see if it works.