Seems like you beat me to my plan to make a Neural Network based variant and I really like the results (especially that they stay a topic instead of totally drifting off into fun nonsense like my Markov Chains.
Have you tried also using other Stackexchange sites as a source? In my experience they result in more fun questions as they have more "human" interactions (especially the more personal advice based sites) which creates things like: - Do Greeks driving affect the whaling industry? - Essential windsurfing equipment to fish? - Do mountaineers eat grass? - Can I toast