Parallax scrolling One Pager using Skrollr to demonstrate how Hydroelectrical Power works as you scroll down. The concept is well explained and nice touch with the "meta" ending at the bottom with the same website in the iPad;)
This page is a product of norwegian renewable energy producer Agder Energi's community education and sustainable energy production policy. It explains how hydroelectrical power works. It is intended first for a mainly young audience, and for mobile platforms in the classroom (ie pads). It's using interaction to simulate the gravital force that is needed to create power from falling water. Falling water contains energy that is released at is is dropped, first from the sky, then to the generator. Then it is transformed into electrical power, and delivered to your house, where it is used to charge your iPad (for instance).