I've been using Dropbox for a good few months now, and have it installed at work and at home as a way to transfer files between the 2 without resorting to a USB stick. I've also been using it to store non-sensitive odds and ends, like photos of me that I might use as profile pictures, or eBooks etc. Until last week I hadn't really used it as a backup device.Last week I was due to give a MadgexILP talk on Introduction to Digital Photography and realised that when I'd swapped my laptop for a desktop, the slidedeck was one thing I hadn't copied over. I headed off in search of my old laptop and discovered it was still unformatted, but I'd been a bit too thorough and had deleted all the files. I checked the file share in the office, but I hadn't put the slides there either. By this point I'd cancelled the talk, and was preparing to rewrite it. Then I thought about dropbox. I remembered that I'd put the file onto Dropbox to transfer it home and back again, but could only find the background material - photos, mindmap etc. I investigated Dropbox a bit further, and realised that Dropbox saves all previous versions of a file and so all I needed to do was to click the "Show deleted files" link, find my slidedeck and restore it. Job done, I breathed a deep sigh of relief and was able to reschedule the presentation.If you want to get a dropbox account, and fancy getting an extra 250MB on top of your standard free 2GB, then follow my referral, create an account, install the software and voila. We're both 250MB better off.