Scan Tailor is an interactive post-processing tool for scanned pages. It performs operations such as page splitting, deskewing, adding/removing borders, and others. You give it raw scans, and you get pages ready to be printed or assembled into a PDF or DJVU file. Scanning, optical character recognition, and assembling multi-page documents are out of scope of this project.
This project started in late 2007 and by mid 2010 it reached production quality. It's being used not just by enthusiasts, but also by libraries and other institutions. A few books processed by Scan Tailor even ended up on Google Books.