[Developer]

A complete list of keyword suggestion tools

Using the best keywords for search engine optimization is a very important thing when you promote a web site. The purpose of this research is to find something that your possible clients search when they are searching to buy your product, but you should also pick some keywords that have little competition.

For example "free stuff" is a search term that gets thousands of queries every day, but most of the sites in the top results have thousands of incoming links so it would be very hard to compete them, while a search term like "free cellphones" or "free computer stuff" could be easier to chase.

With that in mind I decided to write down a list of keyword suggestion tools. These tools can help you find information on many keywords (eg. how many times a phrase is searched per day) or find you some relative keywords (eg. "free stuff" is relative to "free ipod")

Bellow is a list with all the keyword suggestion tools I found. If I missed something please let me know

1) Google Adwords Keyword Tool.
This is the official tool from google adwords. A great thing that this tool provides is the "site related keywords" which can help you see what keywords are probably used by your competitors.
https://adwords.google.com/select/KeywordToolExternal

2) Overture Keyword Selector Tool
This tool provides related keywords using data from Yahoo's ppc program.
Advertising Your Business with Yahoo! Search Marketing

3) NicheBot classic
This used to be my favorite tool. It is the original nichebot.com tool which displays information from overture and wordtracker but merged.
Keyword research service for search engine placement, Google keyword tracking tools, web site promotion software

4) Trellian Free Search Term Suggestion Tool
Another good tool to get keyword suggestions.
Free Search Term Suggestion Tool by KeywordDiscovery.com

5) Geoland Search Engine Queries
A keyword suggestion tool that displays data from several search engines.
Search Engine Queries Estimates - Market demand estimates

6) 7Search Keyword Suggestion Tool
Another great tool from one of the bigger CPC companies, 7search. You can use it to get keywords and estimated prices (for the 7search network)
7Search.com - Keyword Suggestion - Login

7) Wordtracker Free Keyword Suggestion Tool
Generate up to 100 related keywords and an estimate of their daily search volume.
Free Keyword Suggestion Tool From Wordtracker

8 ) DigitalPoint Keyword Suggestion Tool
Using data from overture and wordtracker
Free Keyword Suggestion Tool (Wordtracker Suggestion Tool & Overture Bid Tool Combined) & Keyword Generator

9) Niche Watch
A tool that displays the competition in your niche. Requires a free account to use it.
Niche Keyword Competition Checker Free SEO Research Tool

10) CheckRankings Suggestion Tool
This tool is similar to google suggest tool (I think they use their data)
Free Keyword Position reports, keyword position monitor, keyword tracker, engine ranking search

11) MS AdLabs Search Funnels
An interesting tool to see how people search a certain keyword and analyze the search behavior that users have.
Search Funnels: Keyword Research: adCenter Labs

12) BRL Keyword Suggestion
This is one of the best tools I found. It uses data from 7 sites to display suggested keywords and estimates on them.
Keyword Suggestion Tool

13) Submit Express Keyword Suggestion Tool
A keyword suggestion tool that uses data from wordtracker and keyword discovery
FREE Keyword Suggestion Tool, Keyword Popularity Check Tool, Research

14) Google Trends
Google trends is great to use after you find some good keywords. The tool will display charts on the search volume that each keyword has. The bad thing is that they don't display charts for every keyword but it still helps a lot.
Google Trends

15) Yahoo Buzz
The same with google trends but this is using Yahoo's search engine for the results and it is categorized.
Yahoo! Buzz

16) Google Zeitgeist
This is the newest tool from Google which displays top queries from the Google search engine on weekly basis.
Google Press Center: Zeitgeist

17) Lycos week's top 50
The top searches from Lycos on weekly basis
Lycos 50 - Divas, Depots & Holidays!

18) Google Suggest
This is not really the best tool but it can help a little. While you type a search term the ajax driven form will display some suggested terms.
Google

19) SEObook Google Suggest Keyword Suggestion Scrapper Tool
This tool is using google suggest to display results, but it also give some extra information
Free Google Keyword Suggestion Tool

20) Keyword Lizzard
Keyword Lizard is a FREE AdWords keyword tool that explodes your keyword lists by creating every possible permutation combination of keywords.
Keyword Lizard, the Free AdWords Keyword Combination Tool!

21) Ontology Finder
goRank's Ontology tool displays related search terms for the keyword you are using.
goRank SEO Tools - Ontology Related Keyword Finder

22) GoLexa
GoLexa displays several information on the sites that a search term returns. Great tool to monitor your competition.
GoLexa - free All-In-One SEO Tool for Webmasters

23) Seochat keyword optimizer
With seochat's keyword optimizer you can optimize your list of keywords. This tool is more useful for cpc campaigns
Keyword Optimizer - SEO Tools - Search Engine Optimization, Google Optimization

24) Bulk Overture Keyword Tool
A tool that helps you do multiple queries to Overture.
Bulk Overture Keyword Tool | Quick Whois

Search Engine Queries Estimates - Market demand estimates

its something new maybe you have not seen it. Keeps up to 25 queries and you can add any query to a total.