Off-topic comment on Leanpub -- Judging from the "best sellers" list, you handle a lot of software-related titles. Yet the categories pulldown in the bookstore has only two obvious software-related topics: the rather specific "Agile", and the rather broad "Software". I wonder whether you might not help browsers discover books of interest, by providing more categories and sub-categories (e.g., distinguish programming from data science, and under programming have separate sub-topics like Javascript, Python, and web).