The NewYork Times ran an article on January 21, 2011 on a study that demonstrates benefits of test-taking as a learning strategy (http://www.nytimes.com/2011/01/21/science/21memory.html). I find the study interesting though not terribly surprising. When the outcomes involve remembering facts and formulas, my best studying comes in the form of self-administered mini-assessments. And if you are looking for a quick flashcard type program to help you with this, check out cramberry.com (I just really like the domain name).
Naturally, the study leaves open just how much taking tests might contribute to deeper understanding or one's ability to connect different knowledge sources. Still, these connections aren't likely to happen if the memorization of key terms and concepts never happens. There is a balance for everyone.