For your keyword research try using KeywordSpy.com - a keyword research technology that will help you know what keywords your competitors are using and how it generates money for them, you can use those keywords to drive traffic to your site and give your business the exposure it needs. It offers Free trials.-

A keyword frequency lookup service offered by Miva, based on recent search phrases. They do not say where their search phrase data comes from.

Tool offered by 7search.com letting one query the search queries, and their frequency, for the last month.

KwMap.net is a complex keyword refining tool, aiming to help you discover new keywords. It is a fact that search engines can only help you in finding something if you know the right keywords.

KwMap.net runs on a multi-gigabyte database of keyword inter-relations. You can search all common concepts and you will be presented with related keywords (eg. 'car' -> 'wind shield', 'formula 1', 'bmw') and keyword variations (eg. 'car' -> 'car parts', 'car insurance', 'rent a car'). We also run pertinent links associated to most of the keywords.

Keyword Discovery collects keyword data from many different search engines world wide and compiles a range of search related statistics.

Knowing what exact search phrases customers use to find your products or services enables you to maximize the available search engine traffic.

The reason for this is quite simple. If your web page does not contain the exact search keywords a customer is using, your page will not be found in the search engine results. Basically this means fewer potential customers visiting your web pages.

Secondly, identifying all the relevant keywords to use in PPC campaigns, such as Google AdWords and Yahoo Search Marketing, provides better coverage and increases ROI. You can target keywords individually setting CPC rates to suit each term, which improves ROI, as you do not need to rely on broad match options which are well known to generate lower conversions.