Open Source Web Frameworks in C#

Gaia Ajax Widgets is an ASP.NET Ajax Framework for easy creating Ajax Solutions. No need to use JavaScript and no learning curve. It works with both Mono and .NET 2.0. Gaia is a very lightweight bandwidth citizen, rather than throwing heavy HTML around, it sends small bursts of commands between client and server, updating the DOM as needed. Gaia also plays nicely with other tools, and you can mix and match it with other AJAX frameworks too.