FlyPath is an innovative file browser and file manager designed with minimum number of features for maximum amount of functionality.
If you've seen NeXT's Workspace Manager, you can detect quite a lot of (intentional) similarity between it and FlyPath.
First, there is shelf. Non-crippled, real, honest shelf.
Which can be used as shortcut to file-system, as drag&drop destination, as drag&drop source, or as intermediate drag&drop step when moving or copying multiple files.
Or you can open files on the shelf by double-clicking them.
Single feature with great functionality.