As far as I know there is no such thing as moon dust in World of Warcraft.
There are several different types of dust, so you would have to ask about a specific one.
World of Warcraft,
World of Warcraft
If you want to have more fun than you already do then, yes!
A lot more people play World of Warcraft than Runescape. It is a more populated website.
world of War Craft
The American film production company Legendary Pictures is behind the movie World of Warcraft. The movie will be directed by Duncan Jones and will be released in 2015.
The obvious answer is World Of Warcraft as it is more popular and better then warhammer. it has over 12 million players
I don't play both of them but World of warcraft is. Because if you seen the commercials for wow it's going to have more players.
Although it is slightly more complicated than that, yes, it is pretty much made of dust.
runescape
The Guardians of Hyjal are a new faction that will be appearing in World of Warcraft: Cataclysm. See the related link for more detail.