The online racing simulator
Ok, I'm a very jealous of .NET right now.
I was reading today's coding horror article about Performance is a Feature, of any web site. At point three he talks about making performance a point of (public) pride, and using the MVC Mini Profiler to profile his .NET stack. I am so freaking jelous of .NET web programmers right now. Mind you not enough to switch to .NET just yet, but still ... Pretty awesome stuff.
ASP.NET MVC is a great Web platform, built on the .NET stack. Obviously StackOverflow is famously written in C#. You can download Visual Web Developer 2010 Express, which gives you Microsoft's complete web development toolkit (and the Silverlight SDK). Also check out Phil Haack's blog*, he is the lead developer on .NET MVC.

* While you're at it, also check out Eric Lippert's blog, he is a lead dev on the C# compiler team.

FGED GREDG RDFGDR GSFDG