On many occasions I have used my adwords account to gauge the level of searches for a particular keyword. It's interesting to see the ratio of search volumes often differ for adwords and overture.
Would be interested to see if anyone else uses this as tool and with what level of success.
I have never heard of anyone using Google Adwords to solely do keyword and market research, although I think that there is good information that can be extracted from Adwords.
>>>>>as an alternative to the Overture Search Suggestion Tool.
Overture's suggestion tool is free........Adwords is not.
There are many great threads here at WebmasterWorld regarding keyword research. [webmasterworld.com]
Here is a thread where someone else is looking for an alternative to the Overture suggestion tool. Keyword Thread [webmasterworld.com]
And it is free to a certain extent, you DON'T have to pay for researching just fill in the ad click continue and off you go :)
If that is what you are looking for then adwords is great.
hope this helps
dazz