Answer the Public - Find out what what questions people are asking Google and more.
Keyword Discovery - Keyword Discovery is a keyword research and analysis tool.
iSpionage - AdWords competitor keywords with the click of a button and monitor competitor PPC landing pages.
GrepWords - Grepwords is an API-first Google Keyword Suggestion Tool.
Keyword Tool Dominator - Keyword Tool Dominator is a keyword research tool to find long tail keywords.
SheerSEO - SheerSEO helps you to track Google Search Engine Rankings for critical keywords. PageRank, Back Links and more.