In our organization we had a request to know how many requests are coming to our SharePoint webservers form different browsers.
While working on this, I got a nice post form Mr. Jaskis Why you need to know this:
To figure out what kind of browser(IE, Firefox, Safari) requests are coming for your application.So that you can make sure your application is compatible with that browser type.
To read complete article, please follow http://blogs.msdn.com/b/jaskis/archive/2008/11/13/logparser-calculate-no-of-hits-for-different-browser-type-from-iis-logs.aspx