Hmm, found this AskMe thread on the topic. There's no standout recommendation in it, though...

I'll be scanning mostly photos and some artwork, but the more I think about it the more uses I can think of for this equipment.

What OS are you running, and what do you want to scan?

I got a great Epson that I'm super happy about last year. I did a bunch of research before I got it - I knew I was going to be scanning a lot of slides and some negatives as well as some pencil drawings for an animation.

Previously to that I had an HP, which was an okay workhorse and that had an oversized bed which was cool.

I got a good deal on the Epson because they were closing out the model, and I was told it was because they were going to do combo printer/scanner/copier/faxes now rather than just the scanner (I wouldn't have liked that as much, I like that it's smaller like this). I've been really pleased with the scanner, and the interface to Photoshop has been much nicer than HP's (granted, my HP was probably from 1998 or so).

My OS is Windows XP. I'll be scanning mostly photos and some artwork.

Get one that the company will support over time. I help out friends and a couple of nonprofits with tech support occasionally. The biggest struggles I have had are with scanners no longer being supported when they are "old" models (often only after 2 years).
My experience with HP is that you keep having to reinstall the drivers, but they do keep these (and the software utilities like Optical Character Recognition, that you need to convert images to text) on their website for a long time. Hp use a clunky script language for their software, which is why you need to reinstall it: once it malfunctions, it will seem as if the scanner does not work until the software is reinstalled from scratch (uninstall, then reinstall). Having said that, my HP is very reliable and produces great scans.
Epson also seem to have drivers going back a long time (to 1995 at least!). The scanners of theirs that I have seen had some hardware faults (broken down), but they were pretty old ... Canon are also a good brand to consider. I'd be less likely to consider less well-known brands, as they may not be around (and probably won't support them if they are) in a few years. Look at the reviews on Amazon, as different scanners from the same brand vary considerably.
Also consider what resolution you need and what you will be scanning. For most pictures -> web scanning, you don't need super-high resolution. 1200 dpi (dots per inch) would be more than enough. But if you need photo scanning from physical pictures for posterity, get the highest resolution that you can. This Canon scanner looks good for that, but it is very pricey.
ALSO NOTE: the higher the resolution and the more colors (fine distinction between colors) that you scan at, the larger the files and the longer the scan and image compression (saving the scanned file) take. I once scanned a big postcard in 16-bit color at 9600 dpi. It took 30 mins approx. and the file filled a BIG chunk of my hard drive ... :-)
Also look at the scan-bed size. I often scan A4 documents (got a lot from when I was in the UK). So I need a legal-size scan-bed. Many US scanners scan only up to letter size and some only take up to 6" x 4" photos.