the os890 project offers several examples [1] which illustrate different myfaces extval features. they also show different approaches to solve common requirements (sometimes multiple approaches per requirement). beside some comments each example contains a README.txt which summarizes the illustrated features of the example. an overview is available at [2].
besides these examples extval itself also provides examples at [3] [4]
[1] http://code.google.com/p/os890/source/browse/#svn/trunk/java/web/jsf/extval/examples
[2] http://code.google.com/p/os890/wiki/MyFaces_Extensions_Validator_Example_Overview
[3] http://svn.apache.org/repos/asf/myfaces/extensions/validator/trunk/examples/
[4] http://apache.org/dist/myfaces/binaries/
