Google Analytics for WordPress

• With more than two million downloads, Google Analytics for WordPress is the most popular Google Analytics plugin available for WordPress sites, as of September 2011. Its features include Google Analytics API integration, automatic site speed tracking, outbound links and download tracking, integration between Google Analytics and Google AdSense and custom variable implementation for tracking meta data by WordPress post author, post type, category, publication year or tags. Google Analytics for WordPress requires WordPress version 2.8 or higher.
  
  

Google Analyticator

• Google Analyticator runs a close second to Google Analytics for WordPress in terms of number of downloads. Its features include outbound link tracking, site speed tracking, administrator tracking exclusion, complete options customization and multiple language support. It also comes with a handy administration dashboard of its own that displays 30-day analytics trends on a graph, as well as summaries of site usage, top referrers, top pages and top searches. Google Analyticator also features a custom widget that can be set up to display analytics information in any widget-enabled spot on your WordPress site. Google Analyticator requires WordPress version 2.7 or higher.
  
  

WordPress.com Stats

• If you’re not signed up for Google Analytics, or if you’re simply interested in trying out something different, WordPress.com Stats is a full-featured and popular plugin that taps into WordPress.com’s own statistics system. WordPress.com Stats is designed to be more streamlined than Google Analytics-based plugins, displaying only the tracking and visitor information that’s most pertinent, such as where your visitors are coming from and where they’re going when they leave your site. WordPress.com Stats requires WordPress version 2.8 or higher. It also requires that you have your WordPresss blog or website hosted on WordPress.com.
  
  

WassUp

• WassUp is another popular analytics alternative to Google Analytics-based plugins. Unlike such plugins as Google Analyticator and Google Analytics for WordPress that analyze statistics over a set time period, WassUp focuses solely on gleaning information about what your visitors do while they're on your site. It tracks such things as the searches they do, the Internet browsers and operating systems they use and the pages they visit. WassUp’s other features include a WordPress dashboard widget with graphical charts, a customizable administration panel and anti-spam functionality. WassUp requires WordPress 2.2 or higher.