Wordtracker offers a database of 340 million search queries from which you can query to build keyword lists for use in search engine optimization and pay per click advertising.

• Database of 340 million real search engine queries compiled from top metacrawlers.
• Simple, exact/precise, compressed, comprehensive, misspelling, lateral, and thesaurus search.
• Returns singular, plural, uppercase, lowercase, and capitalized versions of a search query.
• Returns a list of similar keywords that bear any relation to your search query.
• Displays the search count for each keyword.
• Shopping basket to store your keywords.
• Competition search finds keywords that have few competing web pages in major search engines.
• Set up to 7 projects, where you can add, swap, and delete keywords.
• Allows you to export or email the saved keywords.
• Top 1,000 long and short term search reports.

Benefits:

• Find out what your target audience are searching for when searching for your businesses, products or services.
• Find out what keywords to target when optimizing your web pages.
• Find out what keywords to target when advertising in pay per click search engines.
• Find search terms that have few competing web pages in major search engines, which should make it easier to get top rankings for.
• Spot trends, before your competitors do.

Wordtracker Review by webmastersreference.com:

WordTracker is close to being a required tool for anyone that is serious about optimizing their site(s) for the search engines. This is because knowing how to get good rankings is one thing - knowing which keywords will actually bring you traffic is another.

WordTracker provides you with details on which words and phrases people actually use when the search for products and information on the search engines. This information comes from their partnership with some major meta search engines. The database that WordTracker uses regularly has results from over 300 million search engine queries in it. This means that it provides you with an excellent guide to keyword use.

Now, there are other options for finding out what people actually search for. The most popular is probably Overture's search term suggestion tool. The problem here is that many people don't really understand how their tool works. This results in many people actually targeting the wrong keywords.

The main problems with Overture are:

It doesn't separate singular and plural words. It treats them as the same thing - the major search engines don't.
It corrects common misspellings - most search engines don't.
It re-orders words within a phrase. For example, it would show nokia cell phone and cell phone nokia as the same thing - the major search engines don't.

Now, there are ways around the Overture problem but it requires a good knowledge of how people think - and a lot of guesswork. WordTracker, on the other hand, just shows you what people search for and how many times they did - it doesn't make any adjustments.

Here is an example, do people search for soccer shirt or soccer shirts? I would guess that they search for soccer shirt. Overture shows that 2748 people searched for soccer shirt last month - they show nothing for soccer shirts so the numbers must be combined. According to WordTracker, soccer shirts will be searched for 114 times each day whilst soccer shirt is only searched for 11 times. So, following Overture, I'd make a big mistake.

WordTracker also offers a number of other helpful tools in addition to it's keyword suggestion capabilities. It can also give you an estimate of how many searches are made on each search engine each day and it also gives you an idea of how competitive each keyword is. The KEI analysis as its called, seems to be based on how many listings the search engines show. To be honest, this isn't a great way to test the competition but it is, in a way, useful.

WordTracker is available as a subscription and you can choose the length of time that you sign up for. Here is what I would recommend. Before signing up, decide on what your needs are. If you are adding content to a site or creating new sites every week, I'd suggest you go for the 12 month subscription.

If you are just about to set up a new site and want to do keyword research, you have the option of a daily, weekly or monthly subscription. If you think that one day would be enough, just make sure that you sit down before you sign up and brainstorm a list of hundreds of potential keywords. This will ensure that when you do sign up, you'll be ready to get the most out of it.

WordTracker is a very useful tool and definitely something that anyone who owns a site should take advantage of.

1 Day - GBP£4.20 / US$7.46

1 Week - £14.00 / $24.86

1 Month - £28.00 / $49.73

1 Year - £140.00 / $248.64

"The database comes with a 30 DAY money back guarantee. Use it and try it for 30 days and if it doesn't fit in with your need you may claim your money back no questions asked". - Wordtracker