Windows only: PureSync is a user-friendly file syncing and backup application. If you've been putting off messing around with syncing files, PureSync's simple profiles and smooth interface might just lure you into data safety.
PureSync walks you through creating your first profile on its first run. You can create a profile to sync folders, back up folders, or create a profile for your digital camera which—similar to the feature in Picasa—will ignore photos on your memory card you've already downloaded to your computer. You can set filters based on file type, and specify that the particular profile only be executed manually, when a device is connected or a folder found, when files have been modified, or on a user-defined schedule.
When in comparative view, as seen in the screenshot above, you can use the menus or hot keys to quickly force a file comparison based on file names or binary content, highlight the files that will be synced, and highlight file conflicts between the two locations. For those with web space or remote servers, PureSync can synchronise and backup to local drives or network folder and over FTP.
For more potential backup options, check out the Hive Five: Five Best Windows Backup Tools. Puresync is freeware, Windows only.