404 Error Log allows the blog administrator to track 404 pages error generated by the blog, and save the reports into an HTML file or send it through email. (English download)
Local Analytics is a WordPress plugin for integrating Google Analytics, the free web analysis service by Google, into your WordPress powered blog.
TabStat allows you to monitor the status of and optimize your database tables.
Is the plugin for the Google Analytics a widget? Like once downloaded to wp-content, would it then show up under the presentation section as a widget?