Thunar is a new modern file manager for the Xfce Desktop Environment. Thunar has been designed from the ground up to be fast and easy-to-use. Its user interface is clean and intuitive, and does not include any confusing or useless options. Thunar is fast and responsive with a good start up time and directory load time.
GNOME Commander is a “two-pane” graphical file manager for the GNOME desktop environment. GNOME Commander aims to fulfill the demands of more advanced users who like to focus on file management, their work through special applications and running smart commands. 
7-Zip is actually a file archiver with high compression ratio. But, it also features an excellent file manager.
Nautilus is the official file manager for the GNOME desktop. The name is a play on words, evoking the shell of a nautilus to represent an operating system shell. Nautilus replaced Midnight Commander in GNOME 1.4 and was the default from version 2.0 onwards.
Krusader is an advanced twin panel (commander style) file manager for KDE and other desktops in the unix/linux world, similar to Midnight or Total Commander. It provides all the file management features you could possibly want.