It should not come as a surprise that Microsoft has a few hidden features in the leaked build of Windows 8.1 9385 that they likely did not want to be seen by the end consumer before the feature was fully implemented. While there are still gems likely to be discovered, Bavogames on YouTube has put together a video on how to enable some of the hidden items in the latest leaked build.
The tutorial is quite simple to follow and requires you to download (at your own risk) an application that automates the process. The video then walks through some of changes that were applied after you run the application for you to play with at your own leisure.
Windows 8.1 will be released later this year with expectations that it will likely hit RTM around the August timeframe and Microsoft has already confirmed that a public preview will be released at BUILD which takes place in late June.