Statsignal - Statsignal is a simple and cost-effective way to monitor your website or server and publish a status page of your system.
Google Analytics - Improve your website to increase conversions, improve the user experience, and make more money using Google Analytics. Measure, understand and quantify engagement on your site with customized and in-depth reports.
OnlineOrNot - Uptime monitoring for software teams (even teams of one).
Hitsteps - Hitsteps provides tools is a tool offering web analytics, live chat and page analysis.
Site monitoring - Free open-source website monitoring software, easy to set up and use for monitoring web sites.
Clicky - Clicky Web Analytics is a simple way to monitor, analyze, and react to your blog or web site's traffic in real time.