Folder Marker is a handy shell extension that enables you to quickly change folder icons to indicate a priority level or project status (high, low, done, half-done, planned etc.), or you can use it to mark a folder with a special icon or color of your choice. Simply right-click on any folder and select the icon or color to be used from the newly added menu option. Folder Marker supports single and multiple folder selections and is freeware.
Free download