A TreeView is a common means for displaying and navigating hierarchical structures (like file systems) in a GUI.
There's unix program I've come across at an old job, called Tree I think, that does a similar thing at the command line, except instead of a tab delimited tree structure, it gives you combos of | and - to show the structure.
Yep, "tree":
somebody@somewhere:~$ tree example
example
|-- bar
| |-- ben.c
| `-- bill.c
`-- foo
|-- otherfile.txt
`-- somefile.txt
2 directories, 4 files
See TreeMap for a completely different (and much more compact) way to represent a file system (or other hierarchial structures).