krusader is a dual-paned file manager for KDE. It runs on Linux (of course), MS Windows, and Mac OSX.

Folder sync is what makes krusader outstanding, even if you don’t care about dual-pane file management. Open the two folders you want to sync in the panes and go to Tools > Synchronize Folders. You can synchronize both ways, exclude files, delete lone files, etc. Very powerful.

Being a KDE app, krusader does not skimp on features, so there are lots of other things that krusader can do.

link: krusader.org