Popular Mechanics reports: [edited]
In a collaboration between Google Chrome and Lego, digital versions of the classic childhood toy are available online. Google invites new users to begin at the Build Academy, where web tutorials teach you how to construct your Lego creations.
A normal complement of 13 different bricks is satisfactory for most basic buildings, but an "Extras" tab includes ready-made doors, windows, and other Lego odds and ends for more enterprising souls. Once your piece de resistance is complete, you can share (via Google+) your creation with others.