Few days back I came across another cool AJAX Engine called AjaxMagic.Net. The cool & best thing about AjaxMagic.NET is you don't need to write any JavaScript code or any client side script just integrate it and program the regular ASP.NET way code behind or code inline. It’s very easy to integrate just three steps and it’s done. AjaxMagic.Net is free & open-source Ajax engine available for both the .NET frameworks 1.1 as well as 2.0. You can download it here http://www.magicajax.net/Default.aspx/tabindex/1/tabid/29
AjaxMagic.Net article on codeproject.com
http://www.codeproject.com/ajax/magicajax.asp