using flashcards to learn a programming language

Hello, i came across supermemo.net thanks to the hint from Andy in his last book (Pragmatic 
Thinking and Learning). I've found it very useful for learning a foreign language (I'm not an 
english native speaker).
After some research, i came across another website, yoyobrain.com. This one is the social 
version of supermemo.net, meaning that everyone can share his flashcards with other users, 
creating a sort of community of learners. I'm currently looking at the ruby and ruby on rails 
flashcards, but there are a lot more to pick from. How do you guys think about this method 
of learning? Do you know other similar services?