All platforms with Firefox: Even though Firefox 3 has decent file and FTP browsing built-in, the Firefly extension aims to turn the 'fox into a robust file manager. Browse your local drives and folders in Firefox using Firefly, which offers tabs, can split your screen to view several folders, preview images, open, rename, copy, and delete files, and display a hierarchical folder tree in the sidebar. Not sure Firefly is quite as polished as it could be, but if you're dying for a Windows Explorer alternative and Xplorer 2 and others like it aren't cutting it, Firefly is an option. See this Firefly tutorial for more of what it can do. Firefly is a free download which works (almost) wherever Firefox does—the developer says definitely Windows and Linux, but less testing's been done on the Mac.