Dropbox - Put simply, Dropbox makes synchronizing your files across Windows, Mac, or Linux systems a very simple, almost magical process. Put a copy of what you're working on or want saved in your Dropbox folder, and it's synchronized to your account, which has 2GB to start with, and gets bigger if you recommend friends. When you're at another one of your own computers, your Dropbox updates and grabs those files. If you're at someone else's system or on a smartphone, head to Dropbox's mobile-friendly site and grab what you need. It's not quite a backup tool, but it is one of those utilities that makes a lot of old habits—thumb drive copying, CD burning, multi-email self-mailing—seem unnecessary. [Download]