http://www.fjax.net/

Fjax is an open, lightweight, cross-browser methodology for Ajax-style web 2.0 development.
Fjax is a technique focused on drastically streamlining the XML handling layer of web 2.0 applications by parsing the XML in Flash instead of through the browser. Picture Ajax's XML parsing and handling with less than 65 lines of code! It's not a replacement for toolsets that provide presentation-layer visual gizmos. Think of it as a new engine to put under the hood of all the great widgets that are already out there.