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.