I have just downloaded Anthem.NET, another library for using AJAX features in ASP.NET applications. First its an open source project and is hosted at SourceForge.NET. And the best thing about Anthem.NET is, it can be used with both ASP.NET 1.1 and 2.0. Soon after Atlas release, I always wanted to have some kind of similar library for previous version of ASP.NET.

By adding Anthem.NET library and some scripts, you can use AJAX features in the form of server controls. Just like Atlas, Anthem.NET provides server side control model for ASP.NET. Nearly all existing server controls are now AJAX enabled with this tool, and we can make our existing web applications AJAX enabled in no time. The only thing needed is to replace <asp:> tag with <anthem:> tag. Cool isn't it :)

You can read more about Anthem.NET here.
Download Anthem.NET from here.