All log analyzers do almost the same things. They take your log file, parse it and build reports by grouping or filtering the extracted data. Then you explore resulting tables or charts trying to figure out what is going on your web site, proxy server, firewall etc.
Good log analyzers create "multilevel" and cross-linked reports. For example, when you see a page views report, you can click a certain page name and see visitors who accessed this page on any day, or a list of referrers that led visitors to this page. Normally, all these reports are pre-built and statically linked.