Monoprice RJ-45 Color Coded Strain Relief Boots
A nice but optional add-on to ethernet cables that helps to relieve undue stress and strain that sometimes might otherwise break off the ethernet clip if the cable gets tugged on.
Be sure to get the color that matches your cable. I think white is the least eye-sore color if wires will be exposed throughout the house. Blue would be a good option if exclusively going behind walls, so that it's immediately noticeable if you or a contractor ever need to do work behind the sheetrock wall.