There is a keyboard shortcut to place the current folder in the dock. The shortcut is not listed in the Finder menus.
When you hit Command+Shift+T, the currently selected folder in Finder gets a shortcut in the Dock.
[crarko adds: Pretty simple, but yes it works. It does show up in the Finder's File menu if you press the Shift key, replacing Command+T (Add to Sidebar).]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20111028005232272