PathFinder at MacZotPathFinder is an Apple Finder replacement. Why spend $24 on PathFinder when the regular Finder is free? Because PathFinder is more convenient than the Finder:
Snow Leopard improvements - 64 bit build, QuickTime X, Exposé improvements, and more.
Dual Pane File Browser - View the contents of two folders or volumes side-by-side in one window.
Drop Stack - Freeze drag & drop operations by placing files into a temporary stack.
Tabs & Bookmarks - Use the best features of a web browser in your file browser.
File List Sorting & Filtering - Sort by folders first, or limit a list of files by name or extension
Command-Line Tools - Path Finder puts a terminal right in your file browser, and provides a graphical interface to some popular UNIX utilities.
Much, much more - Subversion plugin, Application Launcher, Selection tools, Create and Convert Disk Images
Here is a movie illustrating PathFinder's features.
I think that PathFinder will be most attractive to "power users" who find themselves dealing with files in multiple locations on their Mac and who take advantage of more advanced tools like the Terminal. I realize that even $24 may seem like a lot to spend, but if you are like me you likely use the Finder more than any other application on your Mac. It shouldn't take long to realize a significant time-savings using PathFinder.
As luck would have it I have been demoing PathFinder the past week; at 40% off I do believe that I will pull the trigger and get it...