Netmonitor is a real-time web analytics tool that helps you improve your website, develop your online marketing and get more customers.

GoSquared - watch your site's traffic unfold via a well thought out dashboard.

Chartbeat shows you real-time traffic to your website and allows you to set alerts for any downtime or spikes in traffic.

Woopra features real time web analytics, live chat, and web statistics including tracking conversion and funnel reports. Mashable and ReadWriteWeb seem to use this tool.

User-friendly interface, seamless integration with FeedBurner and Twitter, its own URL shortening service with click tracking visible directly in your account and a Spy feature that allows you to see what visitors are doing on your site as they do it.

This tool uses heat maps to help closely monitor mouse movements and clicks of the user. Useful for optimizing the performance of your pages based on heat map data. The free version is too limited.

Google Analytics is the enterprise-class web analytics solution that gives you rich insights into your website traffic and marketing effectiveness. Powerful, flexible and easy-to-use features now let you see and analyze your traffic data in an entirely new way. With Google Analytics, you're more prepared to write better-targeted ads, strengthen your marketing initiatives and create higher converting websites.

Customer Experience Analytics by ClickTale - discover everything visitors do on your website. Watch Visitor Recordings, Mouse Move Heatmaps, and Form Analytics.

Lucky Orange lets you see what people are doing on your website, in real time, and interact with them in neat ways including live chat.