Google Keyword Tool : plan your campaigns and learn what your cus- tomers are looking for.
Google Trends : subscribe to get Trends email alerts for the topics you care about.
Wordtracker : reveal high performing keywords in minutes (Paid).
LongTail Pro : find profitable keywords faster (Paid).
Market Samurai : discover the best keywords and your competitors weaknesses.
UberSuggest : free keyword tool that makes good use of different suggest services.
Hittail : long tail keyword tool, to help you increase your organic traffic (Paid).
Quality Check : this tool will help you improve your backlink profile.