Gibberish I guess. Doing a lookahead for letters was how I started, and its kinda interesting to see how it turned out as a quick project. Storing the probabilities for each letter given a string prefix is the limiting factor, and took a bit of effort to get it to reasonable size for a browser. I think using words instead of letters may result in better sentences with the same amount of space though...
I think this is a really neat side project. It's almost like a chatbot where you drive. If you can get sentence structure working by doing intelligent stuff with the tokens it could be even cooler. What do you do fulltime?
I build web trading apps for banks. Big, big javascript apps that stream prices and handle trades. Not the kind of apps that require shakespearean spam though...