Traditional Keyword Suggestion Tools
* SEO Book Keyword Suggestion Tool - tool shows top keyword phrases from Wordtracker.
* Wordtracker Free Keywords - free keyword suggestions from Wordtracker. Wordtracker also has a more advanced paid version, and sells top keyword reports.
* Google AdWords Keyword Suggestion Tool - recommends keywords based on a keyword you enter or a URL you have the tool analyze
* Google Suggest Tool - shows frequently search for phrases starting with the words and letters in your query.
* WordStream Keyword Tool - allows you to export a list of thousands of keywords for free.
* Keyword Discovery - free keyword tool from Trellian. Trellian also has a more advanced paid version of Keyword Discovery.
* Microsoft Keyword Forecast - shows predicted Microsoft search impression count and historical trends.
* Wordze - nice for generating decently large keyword lists quickly and inserting them into paid search campaigns.
Keyword Valuation Tools
* Google Traffic Estimator - shows the estimated bids prices and ad clicks for the top ranked AdWords ad. Allows you to check for [exact match], "phrase match", or broad match.
* Google Search Based Keyword Tool - shows keyword search volume estimates and keyword values...by keyword, site, or category.
