4Pane is a highly configurable Linux file manager. It has dual twin-panes, each of which has a directory tree-view pane and a detailed-list pane for files. Advanced features include undo/redo, archive management, multiple renaming and user-defined tools.
4Pane 0.7.0 has now been released. Apart from bug-fixes, the main changes are: it's now possible to overwrite files inside virtual archives (instead of only being able to store duplicates); the Options dialog has been altered, and this and several others made smaller so that they'll fit on a netbook screen; various changes to make 4Pane more locale-aware.
Binaries are available here for the latest versions of Ubuntu, Debian, Mepis, Fedora, OpenSUSE, Mandriva and Slackware. Packages for older versions of these distros, plus Gentoo/Sabayon, Zenwalk and Puppy, can be found at http://www.4pane.co.uk, which also has repositories for those distros that use them, and source and debug packages.