Konqueror
K desktop environment homepage, kde.org
http://www.konqueror.org/
Krusader
Krusader is an advanced twin panel (commander style) file manager for kde 3, similar to midnight or total commander (formerly windows commander), and 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.
http://krusader.sourceforge.net/