Silverlight, WPF, OData (was amazing for hooking your backend up to client-side tables, rubbish at everything else), WWF (Windows Workflow Foundation), WCF (tha

Silverlight, WPF, OData (was amazing for hooking your backend up to client-side tables, rubbish at everything else), WWF (Windows Workflow Foundation), WCF (thank god). All dead. And those are just the ones I can think of from the top of my head. Plus the terrible excel VBA replacement they made, then abandoned, and now it's some fiddly javascript mess. I'm sure there's a ton more people can add. Those are just the ones I personally wasted time on. And let's not forget Window Mobile! Edit: They've also gone through a stupid amount of changes in the asp.net MVC model in quite a short time. Plus constantly seem to overhaul their consistently overcomplicated authentication/authorization system. The state it's in at the moment is shockingly bad.