UltraExplorer was designed to be the ultimate file manager and can be used to replace Windows Explorer. It sports many additional features such as a customizable user interface, favorites window, filter window, history window and even comes with the option to run the command line window from the current directory. The best part is, you can do all of your file navigation from your USB device.
UltraExplorer - Portable File Manager Screenshot:
License: Freeware
Authors Website: http://www.mustangpeak.net/ultraexplorer.html
Download: You can get the portable version of UltraExplorer HERE