Available at http://www.huyng.com/bashmarks-directory-bookmarks-for-the-shell/. Download the current version from here.

Commands:

s <bookmark_name> - Saves the current directory as "bookmark_name"
g <bookmark_name> - Goes (cd) to the directory associated with "bookmark_name"
l - Lists all available bookmarks

“All of your directory bookmarks are saved in a file called “.sdirs” in your HOME directory. Anytime you want to delete a bookmark, just open it up and delete the corresponding lines.”