Keyword Surfer - Get search volumes & keyword data directly in Google.
Content Idea Generator - Free tool creates ideas for your content marketing strategy
Ubersuggest - Want more traffic? Ubersuggest shows you how to win the game of SEO. Just type in a domain or a keyword to get started.
Content Marketing Stack - A curated directory of content marketing resources
Keyword Tool & Content Assistant - Content optimization tool to boost your rankings
Keywords Everywhere - Free browser add-on for keyword volume, CPC & competition