One of my scanners is a Microtek ScanMaker 4800, You can define different scanning areas (I split it into quadrants) and then position a card into each quadrant - it then performs 4 separate scans and automatically names them. I'm not very good at positioning them though and sometime they get a bit skewed. I also have an old Epson which I love. It automatically recognises the edges of documents, scans them separately and does a terrific job of automatically correcting color. Its also super fast. It works best with three or few docs at a time and it does tend to crop the edges a bit, doesn't work very well with non-color cards so I have to scan and crop them manually or use the other scanner for my b/w cards.
