This utility gives you a little control panel on the side of OS X open/saves that lets you select recent places you’ve been in the Finder, recent places in the open/save, let’s you assign hot keys to favorite folders, always brings you back to the last file you opened, let’s you assign a default folder per application (hence the title), and many other cool things.
The latest release adds a dialog at the bottom of the open/save to type Spotlight comments into when you save a file. This is the huge missing feature in Tiger, IMHO. When you are saving a file, that’s the obvious place to add key words.