It takes a while to load, and the site seems pretty rickety (I really hope posting it here doesn't bring it down), but once it loads up, you can realize just how powerful a tool it is. Put your mage talents in, use the checkboxes at the top to fill out info about your gear and situation, and then the tool will show you average hit calculations,damage per mana spent total, and even all of the damage coefficients (up to 2.0.1, so Arctic Winds hasn't changed here yet) on each one of your spells.
Pretty incredible tool for mages, especially for those who want to squeeze every possible bit out of their class and spec. Jonaleth uses the guide as proof that frost mages don't get to churn out nearly as much damage as fire mages do. Well, umm, yeah. What else is new?
But Jonaleth is right-- this kind of tool does provide a really clear look at what we already know to be true. Now you can see in raw numbers just how crazy powerful Pyroblast is.