I'm very inspired by this application because using the combination of the API and the browser is a very flexible way to make sense of the game history ( either creating an opening book as in the OP, or charts which is my whimsy ).
I already have the candlestick charts in my offline standalone interface but this is very cumbersome ( start the interface, download the PGN, compile the charts, takes ages ).
I'm talking about charts like this:
smartchessguiapp.github.io/chartpage.htmlI have my own rough shot trying to aggregate the history from 100 games block:
smartchessguiapp.github.io/ligames.htmlHowever with this I'm running into the problem, that even if I wait 2 seconds between requests, after a few automated requests the server denies service. I have to find a mechanism to cache game history and only add pages that are missing.