GrowthList - A crowd-sourced list of growth hacks
Maker Swipe File - 100+ high-performing Tweets to help you grow your audience
GrowthHackers Projects - Growth collaboration software for teams 📈
Narrow - Narrow helps you build a targeted audience and increase your influence on twitter.
Marketing Examples - A gallery of real world marketing case studies. Updated every day.
Tweetflick - Save, organize & find Tweets to get the most out of Twitter