The Clutter Cookbook provides a series of recipes — quick code examples and discussions for common problems — that help you understand how Clutter works and how to use it correctly while you write your own application.
The Clutter Cookbook is part of the Clutter distribution, and it’s available online here.
Clutter contains a number of basic demonstrators of the possibilities of the API in the form of simple self contained examples. In addition to this, the repository also contains a number of ‘toy’ applications which show off the key clutter concepts and the use of the API. (NB: the toys generally build with the current stable released version of Clutter, rather than the latest development version in the repository.)
Any developers intending to implement their own toolkit on the top of Clutter are encouraged to take a look at Mx, a UI toolkit created for use in MeeGo user experience for Netbooks. It contains a number of useful features, extras, and techniques that can be built upon.