Really Good Emails - A large collection of good product email design.
Growth Hacker Marketing - Ryan Holiday's book, re-released and expanded
Good Sales Emails - Best sales emails from great companies
Ryan Holiday - We Invest $500k in Sci-Fi Founders.
Great Email Copy - A dose of emails from around the web.
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.