Keyword Surfer - Get search volumes & keyword data directly in Google.
GrowthHackList - 100+ curated growth hacks for makers + early stage startups
Keywords Everywhere - Free browser add-on for keyword volume, CPC & competition
Content Genie by ContentFly - Generate article ideas that will grow your traffic
Keyword Tool & Content Assistant - Content optimization tool to boost your rankings
Content Marketing Stack - A curated directory of content marketing resources