The biggest players on the market are:

   •   Google Analytics
   •   Adobe Site Catalyst (aka Omniture)
   •   IBM Coremetrics
   •   Webtrends
   •   Urchin

Note that these are general Web Analytics tools that have a very similar set of features.

There are a couple of very intersting small players popping up that don't offer everything the tools above offer but are very focused and good at what they do.

   •   Clicky
   •   Woopra
   •   Mixpanel
   •   Click Tale
   •   Chartbeat

A lot of services offer integrated Web Analytics Solutions that are very handy since they have native integration with off site services that may be otherwise hard to measure.

   •   Blogger Analytics
   •   Twitter Analytics (currently being rolled out)
   •   Facebook Insights
   •   YouTube Stats

A Good Analytics Solution is often a mix of technologies and human analyzes.