I'm starting a little OSS project and was thinking about writing it with a free IDE. C# Express was my first thought but I decided to try out SharpDev.
I last looked at SharpDev out a couple of years ago and wasn't too impressed. It seemed a quite unpolished and a little incomplete. Things have changed - alot! The latest version, 3.1, was released just last month and it's brilliant. It can do WPF apps. It has an integrated debugger. It supports IronPython. It even has a profiler!
I'm definitely using this thing.