Recently I purchased a ScanSnap 1300 and I have to tell you how much I love the little device.
It sits on the edge of my desk occupying less room than a sheet of A4 paper. It uses a neat little application called ScanSnap Manager that runs all the time (Activity Monitor tells me it uses less than 102Mb of RAM.) I insert up to about 8 sheets of A4 (it depends on thickness) or anything smaller such as a cash register receipt or a business card and press the little blue glowing button on the right hand side and away it goes. Since it is a duplex scanner it will do both sides of a sheet in one pass and doesn't care with a one sided sheet if you have it down or facing. If you want to be a perfectionist it thinks that the face down side is before the face up side.
ScanSnap Manager then turns it into a PDF with searchable, selectable text. I then have it set to save the scan in a folder called "Scans" in my Dropbox and send it to Evernote as well (you can change that to any software that will cope with being told to open a PDF.). By default it gives the scan a name derived from the date and time but I changed the preference and I just get a name "Scan" followed by a three digit reference. One funny thing, if you rename the files then it loses it's count; the software obviously looks in the folder to see if there is a "Scan001.pdf" and so on. You can also set it to send to email, send to Excel or send to print among others. You can also set it to ask you each time, though if you do that you seem to not be able to specify a non-standard application such as Evernote.
The entire process is so easy that I now scan each piece of mail and every receipt I get. I also scan all those bits you get with a new piece of tech; the warranty, the quickstart guide and so on.
Oh, it's compatible with that other popular operating system, too.
Highly recommended. I can't remember how much it cost me but it was worth every cent.