Crazy Eddie's GUI System is a free library providing windowing and widgets for graphics APIs / engines where such functionality is not natively available, or severely lacking. The library is object-oriented, written in C++, and targeted at game and application developers who should be spending their time creating great games and not on building GUI sub-systems!
These two videos should give you a first impression of the capabilities of CEGUI. To learn more about CEGUI's featureswe recommend you the feature page.
To get a better idea about CEGUI's capabilities you can download the latest stable release the latest code from the "default" (unstable) branch of CEGUI and to build and run our "SampleFramework". For more information on how to acquire the source code you can go here. A video showing how to build CEGUI in Microsoft Visual Studio 2010 is available as well. A step-by-step guide for multiple OS is planned and will be available on our site as soon as possible. Until then we recommend you the Wiki and the Documentation for more information.