- http://freekeywords.wordtracker.com/
- http://www.google.com/trends
Evaluate the trend of your selected keyword phrases
- http://www.google.com/insights/search/
- http://tools.seobook.com/keyword-tools/seobook/
- http://tools.seobook.com/general/keyword-information/
Grabs it's results from Google Suggest, crunch the numbers in a hurry to find what works best.
- http://quintura.com/
A tag cloud style of keyword exploration. This tool helps in narrowing down a good keyword phrase with it's web 2.0 hover-popup suggestions.
- http://www.keyworddiscovery.com/search.html?query
www.Keyworddiscovery.com has quite a few very handy looking keyword and domain search tools, including industry keywords.
- http://www.webconfs.com/website-keyword-suggestions.php
Enter the domain name of a website and this tool tries to determine the theme, and keyword phrases that will return the biggest numbers. It is strongly recommended to only use those phrases that are accurate, to get the best results and bring users to your site who will return because they are finding the content they are looking for.
I found many more, in some cases using the api's of others already on the list, mostly the wordtracker api. Of those, some used hard to read captcha forms before being able to submit your keyword search, making those tools unusable when compared with the ease of other online keyword search tools.