One of the best web log analysis applications is Urchin Web Analytics which was bought by Google. I had checked on the Urchin website about a month ago and saw where they were still charging $199 per month plus extra for high traffic. Now the website points to Google Analytics and it is free. All required is to register for an account and to add a JavaScript to your HTML Head. Logging into your Google account will provide detailed reports.
More importantly:
"If you have an AdWords account, you can use Google Analytics directly from the AdWords interface. Google Analytics is the only product that can automatically provide AdWords ROI metrics, without you having to import cost data or add tracking information to keywords."
You can signup here: Google Analytics