A few years back I did a podcast with Erik Meijer about Reactive Extensions for .NET (Rx). Since then thousands of people have enjoyed using Rx in the projects and a number of open source projects like ReactiveUI (also on the podcast) have popped up around it. Even GitHub for Windows uses Reactive Extensions. In fact, GitHub uses Rx a LOT in their Windows product. My friend Paul at GitHub says they liked the model so much they made a Mac version!