My colleague Jim Pierson on the Live Services performance team released the Visual Round Trip Analyzer tool to the web. You can download it here.
Jim works with all the live and MSN teams on analyzing and improving performance of Microsoft web properties, specifically focusing on end-user response times.
Jim and his team built this tool and use it to analyze whether or not a site is optimized for the internet. The tool uses NetMon to capture network traffic, then analyzes the traffic.
One screen visualizes network connection, port, and bandwidth usage:
Another screen rates web pages on various metrics. This screen analyzes the top things Jim's team looks for in client perf and automatically rates your pages using the experience and know-how the Live perf team has gathered over the years. There are 15 rules out of the box.
See Jim's MSDN article here.
If you are working on end-user performance, this is a great tool you can use to analyze your site and quickly find specific ways you can make it faster.