1. Google Gravity - Browse Google in a gravity enabled environment where you can throw page elements around and watch as they bounce off the browser walls. It's fun, and if you get bored, you can simply start searching.
3. Browser Ball - Play around with a ball, throw it around with your mouse and see how it follows the laws of physics. You can also create new windows and see how it moves from one window to other without breaking motion.
4. Wavy Scrollbars - Move your mouse over the scrollbars to create waves.
Other than these, there are many other interesting experiments like JS Fireworks, Browser Talk, Solitaire, Google Sphere etc. It's definitely worth a visit in your free time.