MagicAjax.NET is an open-source library designed to make it easier and more intuitive for developers to integrate AJAX technology into their web pages, without replacing the ASP.NET controls and/or writing tons of javascript code. MagicAjax initially appeared as a codeproject article. Now it is hosted on Sourceforge and a 0.2 version supporting NET 1.1 and NET 2.0 is coming soon. Until then you can try this unstable cvs snapshot.