Google Louches Campaign Optimizer?
It is a free AdWords tool designed to help you fine-tune your advertising campaigns. When you run the Campaign Optimizer, we automatically analyze your budget, keywords, and landing page, and create a customized proposal for your campaign. You can then review the proposed changes and accept the ones you want to apply.
You can reach the Campaign Optimizer via the Optimize Campaign link on your campaign details page. You can also go to the Tools page of the Campaign Management tab and click Campaign Optimizer.