There is also http://mcatquestionoftheday.com/
In my opinion there are two types of good MCAT practice questions. The first are the questions that faithfully replicate real AAMC questions. Doing well on the MCAT is about performance and you have to practice with real AAMC questions to perform well. There is second type of useful question though. These are 'teaching' questions. A teaching question might be a little different, but these are extremely valuable in content review. They are about helping you learn important information and concepts by taking you through the particular kind of suspense and satisfaction you get with viewing a question, thinking about it, gauging your certainty or doubt, and then viewing the explanation. This kind of activity adds impetus to learning.
The question of the day sites are good at making teaching questions. That's what they are about. Both sites do this well, though the site design with the link you gave is a little better. Why not have two questions of the day?