I just recently bought a Fujitsu ScanSnap S500, and I have been incredibly happy with it. I got it from
Newegg.com for $400, and then there is a $50 mail-in rebate on top of that. It has a 50-page auto document feeder, and does duplex scanning at up to 18 pages per minute (36 images per minute). The device is blindingly fast for personal use, and produces great looking output even on lower quality settings.
It has a button on the cover that supports scanning directly to PDF, and you can use the included software to create profiles for the settings you want to scan with (resolution, OCR, duplex, etc.). It also includes a copy of the full Acrobat 7.0 Standard in the box, which makes the price even more attractive.
The final feature worth mentioning is just how incredibly compact this scanner is. The document feeder and output tray both fold up quickly and easily, forming a kind of "lid" for the scanner when you are not using it. The scanner even automatically powers down when you have the feed tray folded down. When in this folded mode, the scanner is just 11" wide and 6" deep, making it perfect for desktop use.
The only caveat, which may or may not be a big deal depending on your use, is that this scanner is not TWAIN or ISIS compatible, meaning that you must use Fujitsu's software to perform your scans. Thus, the scanner can only output PDF and JPEG files, which you then have to open in whatever application you want. This wasn't a problem for me, as I bought the scanner almost exclusively for producing PDF files from all the paper in my office. But it definitely bears mentioning in case your needs are different.
I hope this rambling, voluminous post is in some way helpful to you.
