Imagine if you could set different color to different folders to select the one you want from a huge pile of folders. Rainbow Folders is a freeware which allows you to set custom colors to various any folder. You can easily color any folders to any color you want.
It will easily speed up your navigation among thousands of folders located on your hard drive. You could mark important folders as red, working folders as blue, music folders as well green. However, my color sense isn't that good.
Once a folder is colored, it is visible in every Explorer window, every open/save dialog and in every folder selection tree as seen in many programs. You can also set a custom tooltip to be displayed with the folder every time the mouse comes in focus. And it does works with Windows Vista as well.