AWStats is a free powerful and featureful tool that generates advanced web (but also ftp or mail) server statistics, graphically. This log analyzer works as a CGI or from command line and shows you all possible information your log contains, in few graphical web pages like visits, unique vistors, authenticated users, pages, domains/countries, OS busiest times, robot visits, type of files, search engines/keywords used, visits duration, screen size, HTTP errors and more...