ASCII Library for Creating "Pretty" Directory Trees?

That oneliner is pretty cool, I'd recommend using the tree util.

bash-3.2$ mkdir -p this/is/some/nested/example
bash-3.2$ mkdir -p this/is/another/super/nested/example
bash-3.2$ mkdir -p this/is/yet/another/example
bash-3.2$ mkdir -p this/is/some/nested/other/example
bash-3.2$ tree this
this
`-- is
    |-- another
    |   `-- super
    |       `-- nested
    |           `-- example
    |-- some
    |   `-- nested
    |       |-- example
    |       `-- other
    |           `-- example
    `-- yet
        `-- another
            `-- example

13 directories, 0 files

I realize this question was answered ages ago, but I just found this program called tree which is pretty cool too.

How about this example from Unix Tree / Linux Tree:

ls -R | grep ":$" | sed -e 's/:$//' -e 's/[^-][^\/]*\//--/g' -e 's/^/   /' -e 's/-/|/'