Mattermark Daily - A curated newsletter of blog posts from investors & founders
HSHTG - Generate, manage, save and edit hashtags just in a few finger tap
Folloh - It brings all the news you want from around the web
HashtagWiki.com - Hashtag Generator Tool
LetterHunt - LetterHunt connects you to 10,000+ niche, active newsletter writers to promote your product.
Hashtagify.me - Free hashtags search engine, with paid advanced analytics