To find the best keywords use adwords to find out how many clicks a niche is getting a day and how much it cost per click. Please feel free to add to this. PAY PER PLAY
If you are using firefox , add this plugin http://seo-search-engine-optimizations.blogspot.com/search/label/firefox this provide more info
Might be link given is wrong - I am getting the mesage "No Such URL at This Domain". Is it http://www.har......./pay-per-click.html instead ? Please check
What do you mean by this? Is this for effective keywords research for the improvement of search engine organic or for pay per click?
I use Adwords for all key word research, as well as RankQuest, SEObook, and the SEO for firefox addon. These are all some pretty cool tools to help you determine: keywords, what words your competitors use and keyword efficiency.