Sponsor This Newsletter - 100+ newsletters ready to promote your product
Kickstart Side Hustle Newsletter - Dwarf-size newsletter with viral marketing case studies
LetterHunt - LetterHunt connects you to 10,000+ niche, active newsletter writers to promote your product.
Newsletter Pilot - Newsletter Pilot helps businesses engage with their subscribers by turning blog articles or any other content into catchy newsletters.
Sponsor My Tribe - These newsletters just want to promote your product/service
Obsidian.net - Obsidian is an Action-Adventure, First-person Exploration, Puzzle and Single-player video game created and published by Rocket Science.