Matus Goljer—Fuco1 of Smartparen fame—blogged a nice bit of Elisp that adds imenu functionality to dired. At first, that doesn’t seem to make sense since an imenu menu would simply have the same information as the dired listing itself. What actually happens is that imenu gives you a list of the subdirectories inserted into the dired listing. You can then jump directly to that subdirectory from imenu
If you think that might be useful, take a look at Fuco1’s post for the details.