My itty bitty part-time startup has a better uploader than Flickr, thanks to Dropbox on the server. Users share a folder with the server and copy photos into it that they want uploaded. They can be choosing photos to upload even with no connection, e.g. traveling with a laptop.

Reliable backups are a big deal on a server, and maybe not as much on the desktop. I mean, I'm not too fussed if my mp3 collection gets stomped by a hard disk failure (I just download it again from emusic), but if tens of thousands of forum and ticket tracker posts are lost, I'm gonna be devastated. And, having it in a shared location that makes it easy to copy the database and website to a development machine might be cool. (I'm kinda talking abstractly here, as my own products provide tools to solve all of these problems in different ways, but they're things I've had problems with in the past. And, if Dropbox had a server product, we'd probably add it as a backup target option.)

I would even use it commercially in my products but API lacks ability to share folders. For now you have to do it manually.