I’ve been using Drop Box for quite a few months now. It’s simple cloud based storage (ie — storage that exists ‘out there’ … not on your computer) with some nice perks.
For starters, it is completely cross platform (Windows, Mac, Linux) and also has a web interface. It allows you to upload and download any file type without restriction. It also has the ability to share folders and files with other people. Lastly, there is a standalone application that, once installed, will keep files placed in your ‘dropbox’ in sync. I know what you’re thinking — they have you covered everywhere with both iPhone and Android apps (free).
For Drop Box, there are various levels of accounts ranging from free 2 gigs of space all the way up to 100 gigs for $20 a month.
While it seems that Drop Box is in it for the long haul, the one thing that keeps it from being a backup solution is the steep cost-per-gig. I think that, for most people, the free 2 gig will be sufficient. I think that once you get over the 2 gig plan, it might be worth it to look at some other cloud based storage options.-D