Blizzard introduces the [Skill Calculator] which allows you to play around with the skills and passive skills, and explore combinations prior to playing the game.
Best yet, you can link to a specific build — you created in the skill calculator — via Twitter and Facebook.
You can now read the key features of each class, their active skills and passive skills with complete descriptions, and surprise … even what each rune type does to each active skill.
Excited yet? Check it out here.