The single-page NeatReceipts scanner seems to be a nice alternative to the more expensive ScanSnap, but I recently noticed an ad for a new NeatDesk model that offers more flexibility. It's exceptionally stylish, and offers a unique paper feed that lets you queue mixed sizes of documents in a single scanning session. The website says that the new model is already available for the PC, and is "coming soon" for the Mac. The PC version is priced less than the equivalent Fujitsu ScanSnap on Amazon.
I've never tried NeatReceipts, nor any of their scanners, but if you have experiences you'd like to share, please feel free to chime in.