If you click "Start Training" in the upper right, you will be asked a series of randomly generated questions on a topic of your choice. So far I've tried the BST training and Bitmask training. I have to say that this is the best randomly generated quiz system that I've seen. There are obviously some very smart people behind this.
Steven Halim, the person behind this, was my lecturer for the competitive programming class I took in my sophomore year. Super nice guy who is really passionate about teaching!