I saw quite a few document scanners for iOS devices at CES last week, but this is about as elegant as they come. Brookstone is offering a scanner called iConvert, which uses your iPad as the receptable for anything you scan with it. Not only does it scan your documents with a 300 dpi scanner, but it even does a very nifty graphical representation of the document showing up on the screen.
The iConvert is US$50 cheaper than the popular Doxie Go at $149, but of course this scanner is specifically built for the iPad or iPad 2 and offers fewer features than other scanners. There are also a few apps out there (including Scanner Pro) that will let you use the iPad's camera to pull in documents without extra hardware. Those don't work nearly as well, though. If often bring drawings or forms into a digital format, you'll want something more reliable.
The iConvert seems like a solid option, and the fact that it's completely based on the iPad means it should be simple to port around. Brookstone is offering it for purchase next month.