Alternative to Google Adwords Keyword tool

There are a few very useful sites which are very good alternative to Google Keyword tool.

Some of them are free while others are paid.

• Free Keyword Tools

1.nichetaxi
2).spyfu
3)keyword.secretstohighprofit

• Paid Keyword Tools

1)keywordcountry– allows you to maximize AdSense earnings and search over 600,000 niche keywords
2) adwordanalyzer – helps uncover targeted niche markets and maximize AdSense Campaigns
3) keywordelite- helps to uncover niche keywords and analyzes PPC campaign competition