A project I wish someone would write: a friendly GUI that wraps around the scanner library and the PDF library, and lets the user easily scan and file documents.
It would have a toolbar with big buttons: "scan letter", "scan brochure", "scan photo". These would respectively choose high-resolution black-and-white, medium-resolution color, and high-resolution color.
The user would plop down the document and hit one of those buttons. Python would wake up the scanner and have it scan, and then would use Python Image Library or something to auto-detect the size of the actual scanned document and auto-crop down to minimal size.
For "scan photo" you would get a JPEG. For the others, you would get a PDF. And it would have an option where you could scan several pages and then select the scanned pages, and say "group" and it would make a single PDF out of them.
Other useful toolbar buttons would be: "Copy Letter", "Copy Brochure", "Copy Photo". These would scan and then immediately print on an appropriate output device (or just on the default output device for your first version).
If you want to go crazy, you could add an OCR function to try to recover searchable text from the scanned images, and put that in the PDF as tags or something.
Someday I will write this if nobody else does...