Almost two years ago, I discovered a project of Microsoft Research named AJAX View. The project had only a public release containing some client-side plug-in meant to help AJAX applications instrumentation.
Time has passed and the tool has matured and become a full blown extension of Visual Studio 2008 named Visual Studio 2008 AJAX Profiling extension. Go check-out Soma’s blog for more details!
Bogdan Brinzarea's blog 