I am not sure whether multiple choice tests can really assess the knowlege and skill of somebody else, but they help me to check, whether I've really understood a topic and they help me to discover gaps in my knowledge.
Writing such tests requires paying attention to the details which I would probably overlook otherwise.
From time to time I will publish some of the tests here:
I use Ruby to implement these quizzes. If you'd like to publish your own quizzes, just drom me a note. I can give the source code to you or perhaps even publish your quiz here.