Forum Moderators: open
Adwords is a bit better as it will estimate your clicks. I find the main index traffix to be much more than adwords but it is a starting point. Also, you do not need to open an account to use it.
Not sure what you mean by all engines.
Also, this is a very tricky subjects there are SO many variables like; title, description,position, keyword, niche, etc...
I have found that the noraml index gets 3-7x the clicks as adwords, even in the top positions, assuming you are in the top 3 in the non paid index. It will take some research on your part conclude how it works for your terms.
When looking at the adwords keyword tool, keep in mind that unless you use brackets it is uncluding ALL searches that contain your keywords.
The overture tool is not only innaccurate, but has skewed results on certain high-paying terms.
This is because partenrs pre-fill search boxes or return results for particular keywords in popups etc, and these show up as searches even though the users never actually searched for that term.
I think that the Overture Search Term Suggestion Tool gives a rough idea of the total amount of searches for a keyword on the whole of the Internet for the previous month.
If you go to alexa you can fine the top 500 sites and the top sites by category. While this is not exactly what you are looking for you might find it helpful.
Regards
menton
Take a look at where Wordracker gets it's results from. It is not MEANT to be reflective of the traffic on Google. Their monthly sample is about 250 million searches which Google gets evry 35 hours.
Wordtracker is used to give webmasters an idea about WHAT keywords/phrases are being searched and a base for comparison between the various keyord/phrases.