Book Merge is an app by Mary Dickson Diaz with significant help from Joel McCoy. It runs on Sinatra. Book texts are from Project Gutenberg offering over 49,000 free texts from the public domain, and edited for optimal sentence generation by moi using regular expression searches in Sublime Text. The Markov functionality to generate new sentences comes from the markov_chains gem by Justin Domingue. I wrote about my experience building this app here.