Rainbow Folders allows you to change the color the folder icon for any folder you choose.

Download RF.ZIP and unzip it to a folder of your choice.

I quote:

Rainbow Folders (RF) is an easy to use program, which allows you to change color of the icon representing chosen folder to any color you like. What for ? Mainly to boost yours computer usage speed & skills. When you're exploring directory which contains lots of subdirectories in Windows Explorer you can easily commit a mistake, e.g. by clicking the folder's icon which have similar name to the one you really wanted to go. When the folders will be marked with the colors of your desire you won't make any mistake and after some time you'll be clicking the right folders by the impulse. For example you can use RF to mark subdirectory TEMP inside C:WINDOWS. Then after going to the system dir you won't be searching the TEMP dir on the whole screen, but at the start you will click e.g. the eye attacking bloody red folder. And now the best part: you can colorize unlimited number of folders - each into a different color. So you can e.g. colorize to red all important folders, then colorize all frequently visited folders to green etc. Also the effect of colorizing folders is not only visible in Explorer but in whole system, so also in any directory selection tree, and open/save dialog in any Windows application ! But changing colors is not everything you can do with help of RC, you can also set an extra warning when someone will be trying to delete colorized folder, and optional text that will 'pop up' when the cursor stops above the folder's icon for a while. Speed up your work now !