Richard recently authored practice test questions for the three core CRM 4 certification exams. he is having LOTS of other articles on the exams and how to prepare for them in the certification category. So if you are thinking of clearing the MB 631 , MB 632 or MB 633 you must visit this place.
you can test your knowledge with these practice test here
i have gone through the tests and it is really great. try your knowledge there and best of luck :-)