Two of the most common dialog boxes you use are the save and open file prompts. As you probably know, there are shortcuts to common locations available along the left side which allow you to quickly jump to specific folders. If you would like to customize these locations, a simple way to do so is with the freeware utility PlacesBar Tweaker.

With this utility you can add or remove locations in addition to rearranging the existing order. This before and after screenshot should illustrate exactly what the tool does. Pretty simple, yet very useful.