Spacedoo - Short actionable marketing hacks
Narrow - Narrow helps you build a targeted audience and increase your influence on twitter.
Growth Hacker Marketing - Ryan Holiday's book, re-released and expanded
MyFollowers - myfollowers.us is the answer to how to get more free followers on twitter. Start using www.
Primer - CSS toolkit and guidelines that power GitHub
Follow3rs - Follow3rs enables you to add more followers to your Twitter account and become prominent in no time at all.