Part of you search engine optimization of your site should include analysis of your site traffic to see which keywords or pages are working and which ones are not. These site traffic analysis tools consist of both client-side tools as well as server-side tools.

Client-side Site Traffic Analysis Tools

• Google Webmaster Tools
• Google Analytics
• Google Website Optimizer
• ClickTracks

Since Google is the leading search engine as of this writing, their tools are one of the best and they are free. See video about Google SEO tools.

Server-side Site Traffic Analysis Tools

• AWStats - server side logging often found on many Linux shared webhosts