The infamous Q-bank. The reasons I liked it?
1) Excellent quality questions, format very close to the real thing. Very flexible, you can time or not time your tests, choose questions from specific disciplines or randomly, short but clear explanations for every choice, you can test yourself on the questions you had done wrong the first time.
2) Because after spending a long time flipping through books, I would appreciate any change in my studying. Computer is linked in my mind with fun(although the q-bank was clearly NOT fun to do).
3) It prepares you for long sessions of working(not playing games or surfing) in front of a computer screen. This was probably the biggest contribution of q-bank in my preparation.