I have assisted in the creation of several certificiation tests, on a variety of technologies on which I am (or was at the time) considered an expert.
When Borland released Delphi 3, DSW was the author of the courseware and considered authorities on the product and language. Borland solicited developers and writers to help build the certification test, and I contributed to it. I cannot publish the test here because some of the questions we developed are still in use.
ReviewNet is a company that specializing in certification tests to test potential and existing employees on particluar technologies. Their breadth and depth of topics is amazing. They hire test writers in particular specialties within a field to write tests for them. They asked me to write tests for Enterprise Java Beans and Applets. I don't know why they throught I had particular specialization in those two areas of Java development, but I agreed.
Art of Java Web Development
The DSW Group
Manning Publications
ThoughtWorks