These software are no longer maintained.
Dropbox is the easiest way to store, sync, and, share files
online. There's no complicated interface to learn. Dropbox
works seamlessly with your operating system and automatically
makes sure your files are up-to-date. Available for Windows,
Mac, and Linux.
Ubuntu One is your personal cloud. You can use it to back
up, store, sync and share your data with other Ubuntu One