SharePoint Usage Reports (FREE Tool & 3rd Party tools)

Given below  recommend 3rd party tool to enable SharePoint administrators to see web application/ farm usage reports

Open Source : http://www.reportmagic.org/ (Free Report Magic makes usable statistics from your web site log file analysis) 

3rd Party products

1. CardioLog for SharePoint
2. SharePoint Server and Site Administration and Usage Reporting
3. DocAve Report Center for Microsoft SharePoint
4. Nintex 
5. http://www.webtrends.com/