An advertisement post :)
If anybody is looking for a convenient two-pane file manager for Mac OS X - you're welcome to try a project that I'm currently working at -
Files manager. Yep, the name is just "Files". Straight and easy.
It is in alpha stage now, but you can freely use it and send any feedback and feature request if you wish.
You can either use orthodox look with monospace fonts and blue-and-white colors or choose a native mac look - the core and functionality will remain the same.
This app is NOT cross-platform, it can't run on Linux/FreeBSD/Windows/whatever. Files is a native OS X / Cocoa application, tightly integrated with mac-specific mechanics and services.
Hoping you'll like it!