Recently Windows 8 build 7850 has been leaked. The leaked version of Windows 8 revealed many features like Modern Task Manager, Modern Reader, TaskUI, Ribbon UI and webcam. The folks at Windows 8 Beta & Windows 8 Search they have created a tweaking tool Windows 8 Tweaker to unlock following Windows 8 Features.
If you are not sure about editing registry and adding values, here is a tool with GUI that can enable hidden features in Windows 8. Windows 8 Tweaker is a free tool developed by Ankur Mittal (MVP) and Vipul Taneja. Go ahead download Windows 8 Tweaker and hit enable button for the features you wish to enable. There is also an option to enable all features and disable them in a single click.
Windows 8 Tweaker to Unlock Hidden Windows 8 Features
Windows 8 PDF Reader
Windows 8 Ribbon UI
Windows 8 Webcam App
Windows 8 Modern Task Manager
Download Windows 8 Tweaker tool to unlock hidden Windows 8 Features.