Some icons are just obvious enough that nobody should need text below them to tell them what the icon is for. To get rid of the text, right-click on the icon and select 'Rename'. Now hold down the 'Alt' key and type in the number 255 using the keypad only. For each additional icon you want to change, you will need to add 255 an extra time (example: alt+255; alt+255 alt+255; and so on).
NOTE: If you use this tip to change a folders' name, you will not be able to change it back.