Green Tea Press & Humble Bundle
Green Tea Press hosts a number of free e-textbooks which relate to data science and programming. One of our members has started going through a copy of ‘Think Stats’, and says that it’s a pretty solid grounding in analytics. He thought some other members might be interested.
This one is a more generic site, but it includes book bundles which go under a pay-as-much-as-you-wish model, and they frequently include programming/data science bundles, which can be good value for money.