I’m in contact with a company called Active Textbook which aims to produce an electronic reader and a platform for sharing pre-existing content in web ready format. Currently their technology uses Microsoft Silverlight (use Moonlight beta on a Mac) but I asked about moving to HTML 5 and the company spokesperson said that this is in the works.
Here is an example (it will take a while to load, and you may need to install Silverlight first):
