the crutch of any bash, tcsh, or ncftp user. the notion of typing the first few letters of a file or directory and then hitting tab to complete it.

cd /u(tab)X(tab)li(tab)X1(tab)fon(tab)mis(tab)

added note:
zsh has this functionality, much more to a sophisticated standpoint, to the point where it will complete based on whats already been typed on the command line:
In a directory with:

If one were to type:
tar zxvf foo(tab)
zsh will complete to the tarball's filename, as opposed to pausing at the common foo-1.2 of the dirent. This is configurable.