Super Flexible File Synchronizer lets you back up your data and synchronize PCs, Macs, servers, notebooks, and online storage space. You can set up as many different jobs as you need and run them manually or by using the scheduler. The software works with local hard drives and any other mounted volumes. In addition, it comes with support for FTP, SSH, HTTP, WebDAV, Amazon S3, and Google Docs. You can use Zip compression and data encryption. There are powerful synchronization modes, including Standard Copying, Exact Mirror, and SmartTracking.
The new version 5 is now available for Linux. The GUI still has some issues but the functionality is very extensive and has been thoroughly tested on Macintosh and Windows.