Krusader

From the Krusader web site:

Krusader is an advanced, twin-panel (commander style) file-manager for KDE, (similar to Midnight Commander or Total Commander) with many extras. It provides all the file-management features you could possibly want.

Plus: extensive archive handling, mounted filesystem support, FTP, advanced search module, viewer/editor, directory synchronisation, file content comparisons, powerful batch renaming and much much more.

It supports the following archive formats: tar, zip, bzip2, gzip, rar, ace, arj and rpm and can handle other KIOSlaves such as smb or fish. It is (almost) completely customizable, very user friendly, fast and looks great on your desktop! :-)

= Similar applications =
 * http://www.cis.upenn.edu/~bcpierce/unison/ allows you to sync directories as well

= External links =
 * Krusader Home Page