The best, worst user interface
One of the better interfaces I have used would be the visual file explorer. In a more general sense - the concept of a GUI-based directory browser that takes the general directory information from a command line-based system and provides a more visual basis for exploring is what I am referring to. With this icon-based directory tool, one is able to quickly traverse directories, identify file types and associations, and quickly get a host of details about the files. Other features usually include the creation, renaming, and quick deletion of files and folders. The multiple ways to achieve a goal is also quite good. Novice users can use the most intense interaction through input devices to achieve their goal, while more experienced users can learn quick short cut commands that speed up the process for multiple actions. This graphical representation also allows a better visualization of the hierarchy of folders and a better sense of depth, which allows better organization than a command-based directory browser would allow.
There are a few ways that could be implemented to better this interface. Many companies have added a thumbnail feature to folders to show contents inside them and such. The best way to show the contents of a folder is through self-documentation. In this aspect, the implementer is over-compensating for a small percentage of the users. Another design implement would be a bridging of the hierarchy display and the folder display mode, where the hierarchy display shows links to folders in a linked tree view, while the folder display shows really only the current browsing folder. One way to achieve this is for more options when using the hierarchy display such as more display types for files and folders that are similar to the current folder browsing options. While this interface has been used and improved many times, it seems to be the best route at the moment to bridge the visual and command based directory browsing. Any radical changes to this already simplistic design would most likely do more harm than good.