GrepWords - Grepwords is an API-first Google Keyword Suggestion Tool.
AdWords Keyword Generator - Instantly generate thousands of targeted longtail keywords
SheerSEO - SheerSEO helps you to track Google Search Engine Rankings for critical keywords. PageRank, Back Links and more.
PPC Gear - Instantly find where you lose money in Google Ads
iSpionage - AdWords competitor keywords with the click of a button and monitor competitor PPC landing pages.
Keyword Surfer - Get search volumes & keyword data directly in Google.