Free Analytics Tools
These tend to be limited in feature set and give themselves sitewide links on your site, or require you to trust giving a major search engine like Google virtually all your marketing data.
- Google Analytics – powerful full featured analytics tool. Even allows you to track your ROI by keyword for each AdWords ad position. Google AdWords also has internal split testing and conversion tracking software.
- Google Website Optimizer – allows you to A/B split test landing pages and track how well Google AdWords traffic converts.
- Microsoft adCenter Analytics – not publicly launched yet, but accepting invite requests.
- Piwik – open source web analytics program
- Site Meter – starts off as free, but charges for advanced features
- Stat Counter – starts off as free, but charges for advanced features and bandwith usage.
- Webalizer – default log analyzer on many servers.
- Analog – default log analyzer on many servers.
- Awstats – another popular default log analyzer on many servers.
Jonathan Camp 
I use Google Analytics (urchin) for months.
It’s a good product now integrating Adsense + Adwords. This all I need before running my favourite keyword tools…
To Your Success!