Really Good Emails - A large collection of good product email design.
Petit Hacks - Acquisition, retention, & revenue hacks used by companies
Good Sales Emails - Best sales emails from great companies
Growth.Design Case Studies - Product tips… in a comic book format
Great Email Copy - A dose of emails from around the web.
POWr - POWr is a library of free and customizable forms, galleries, social streams, e-commerce, countdowns, and more.