Replacement FOUND! Rated 4 out of 5 stars
I've been looking for an update to this that works for ff3.6 for so long...and I finally found it.
Show Parent Folder. It is up to date, works great and compatible with FF 3.5-3.7
A nice complement to this is Go To Parent Folder.
Rated 5 out of 5 stars
I'm with all these other reviewers. This was one of the most useful addons I ever downloaded.
I even kept my Firefox 2.x installed in large part just for this addon.
Someone PLEASE update it for 3.6 compatibility or create a new tool that performs the same functions.