Keyword Discovery - Keyword Discovery is a keyword research and analysis tool.
Keyword Hero - Keyword Hero is an SEO tool for organic keywords.
GrepWords - Grepwords is an API-first Google Keyword Suggestion Tool.
SheerSEO - SheerSEO helps you to track Google Search Engine Rankings for critical keywords. PageRank, Back Links and more.
AsinSeed - Asinseed is a professional tool specifically dedicated to Amazon keyword optimization.
iSpionage - AdWords competitor keywords with the click of a button and monitor competitor PPC landing pages.