Growth Hacker Marketing - Ryan Holiday's book, re-released and expanded
Maker Swipe File - 100+ high-performing Tweets to help you grow your audience
TweetFavy - The Growth Hacking Tool for Twitter. Marketing automation software / Growth Hacking tool designed to grow your social media influence and attract real, targeted and engaged Twitter followers.
Narrow - Narrow helps you build a targeted audience and increase your influence on twitter.
Primer - CSS toolkit and guidelines that power GitHub
TweetPilot - Grow a relevant & responsive following on Twitter