Spacedoo - Short actionable marketing hacks
Site Rank Data - View historical rank information of websites via time series charts.
Growth Hacker Marketing - Ryan Holiday's book, re-released and expanded
Q-Stats - Get free marketing insights for every question on Quora.
Primer - CSS toolkit and guidelines that power GitHub
Seoxan - check seo report for any website, alexa ranking, server information, meta tags, authority, page speed and more