I have read about the push technologies recently. Using it real-time data streaming is very easy. I also saw an implementation called ajax push engine, but it runs on linux or m
Orbited
Orbited is an HTTP daemon that is optimized for long-lasting comet connections. It is designed to be easily integrated with new and existing applications. Orbited allows you to write real-time web applications, such as a chat room or instant messaging client, without using any external plugins like Flash or Java.
It can be installed as a windows service. The license is MIT.
MethodWorx
MethodWorx was developed out of this series of articles on Code Project. It has an Open Source license.
This is a packaged version of a library the we used in some projects to enable COMET polling or Long-Polling within some of our ASP.NET applications.
It uses an Asynchronous HTTP handler to keep ASP.NET connections open to wait for events to occur, enabling real-time AJAX callbacks.
Lightstreamer
LightStreamer Moderato is free but not open source
WebSync
WebSync is a standards-compliant scalable Comet server for IIS using .NET. It's also available on demand as a hosted service. This is neither free nor Open Source, but does have a free trial.
Other
There are several more Open Source Comet projects: