Blizzard have updated the official Diablo III website with the Class Skill Calculator.
Here's the blurb from the official site:
"Until you get your mittens on a freshly baked copy of Diablo III, you'll want to make use of the class Skill Calculator. You can use this calculator to explore unique builds for your favored class by selecting active skills, Runestones, and passive skills. If you think you've found the deadliest combination for your class, be sure to export your build and spread the word! This feature will allow you to share your creations with your Facebook friends and Twitter followers with the click of a button, or anywhere else on the web you'd like by copying the unique URL."
Other updates to the D3 site include a new Game Guide, that gives you information on the 5 available classes plus place-holders for further content. Add to that a new section called What's New in Diablo III that gives details of the things you can expect in Diablo III, whether you are a Diablo II player or completely new to the series.