If you're a big World of Warcraft fan then you'll probably love WowMatrix which is a free WoW AddOn Installer and Updater that saves precious time manually checking for WoW AddOn websites and downloading AddOns.
To use it just open it before starting World of Warcraft and it will update your WoW AddOns fairly quickly depending on your connection speed. There are literally hundreds of add-ons to choose from that vastly vary in quality (there's more than 1,500 according to the developers) and you don't need to visit a single website. There's no need to worry about WowMatrix overwriting or adding add-ons you've already got because it instantly recognizes any WoW AddOns you have installed before WowMatrix checks to see if they need updating or upgrading.
With tons of add-ons being regularly added, WowMatrix gives you the power to expand WoW like never before.