I bought a Canon N650U about 5-8 years ago and disliked it at first because it only scanned in TIFF. But I had so much paper cluttering up my office at work and the office HP's document feeder has a nasty tendency to misfeed pages so I took it in to work and use CutePDF to do the document conversions to PDF format.
That simple old flatbed scanner has been worth its weight in gold the last few weeks. I was able to throw more than 3 cases of accumulated paper out last week, cleaned up a case of archival documents just today, and have backups of handwritten documents so I can provide management with appropriate paper trails where necessary.
The N650U scans in B&W, B&W from color, grayscale (great for photos), and full color and I just "print" to PDF using Cute PDF.
I'd love to have a NeatDesk for its document feeder, but I think it's $400 price tag (and that of the Brother and HP cousins) is bit steep.
$89 on Groupon? I'll have to look at that. I've got the CamScan app for my cell phone, but then there's about 3-4 more steps to get it saved as a PDF. I'm currently looking at a $69 "wand" scanner sold by WalMart too.