The top of the line would be Fujitsu's Scansnap: there are two version and make sure you get the one for Mac.
It is pricey but sounds ultra-convenient, plus it is has OCR capabilities (if you need it).
I've had my eye on this for a year and I'm just saving and waiting for when I really really need it (I'm a grad student who wants to scan in all my clippings, handwritten notes, odds and ends from the non-digital years).
Now remember this scanner will not be best for images. Check it out. I will envy you if you get it!