the nearest you will find is Overture's search term suggestion tool
which is used by advertisers to determine the most popular keywords.
This also acts as an indicator for keywords in general, as the
Overture search content and results is served across many other major
- United Online
(from Overture's major affiliate partners list)
The closest Google come is with the Traffic Estimator which serves the
purposes of advertisers:
"Traffic Estimator - After you select your keywords, the AdWords
Traffic Estimator automatically provides you with estimates for the
number of clicks per day, average cost-per-click, cost per day, and
average ad position for each of your keywords." excerpt from
The Overture tool is currently the most comprehensive benchmark for
keyword popularity, with the widest scope across it's partner sites.
I hope that helps, if you need any clarification of the answer just