I've been using DropBox for a couple of months now and I'm very impressed. I keep my crucial source code files on there and sleep well at night knowing that they are backed up "off-site." That was my primary goal in using DropBox. However, now, I'm using more of the features and I'm using it to keep my DEV server synchronized with my PROD server with respect to files that have been uploaded by users. This has always been a pain for me to do but now it happens automatically. I've also started investigating the possibility of using it for Continuous Integration in a Cruise Control build environment. I haven't set that up yet but I don't see any reason why that wouldn't work.