If you open a finder window, you will see that there is a "Favorites" icon (heart icon) that you can drag things to, and a shortcut to that item will be automatically created by finder in ~/Library/Favorites. Simply drag the icon for ~/Library/Favorites to the Dock and it'll show up in the right half of the dock where your documents are parked.
To quickly launch a Favorite, just Control-click (or click and hold) on the Favorites icon in the dock and you'll be given a menu list of all your favourites. I even changed the ~/Library/Favorites icon to a ToolBox looking icon. You can change the Icon to taste. Now I can launch frequently used items quickly and easily without having any system bloat (ie better stability).
[Editor's note: Although this is a basic hint, and it's been mentioned here a couple of times in passing, many people may overlook it due to the Favorites folder being somewhat hidden inside the Library folder. If you like this, you may find that a customized shortcut folder works even better. The Apple Favorites folder, for example, won't let you create sub-folders or organize your favorites by type. I created a "QuickLaunch" folder (that's now bound to a custom MaxMenus keystroke as well as living in the dock) that contains folders for types of apps and documents. Within each folder is an alias to a favored application or document. Now I get a small pop-up and can more easily navigate to the favorite item I wanted. The only downside is that you can't just "Add to Favorites" through the menu; you'll need to hand-manage your customized favorites folder, but command-option-drag and spring loaded folders make it pretty easy.]

