Total Commander is a Windows based file management program with the good plugin system.

Dolphin is a lightweight file manager. It has been designed with ease of use and simplicity in mind, while still allowing flexibility and customization.

EasyFind is an alternative tool to Spotlight, OS X's built-in search tool.

XYplorer is a file manager and Explorer replacement for Windows. It's fast, powerful, portable, dual paned, and multi-tabbed.

Unreal Commander is a freeware file manager for Windows.

Archivarius 3000 is a full-featured application to search documents and e-mail on the desktop computer, your local network and removable media.