A free IDE for C#, VB.NET, & Boo projects on Microsoft's .NET platform
SharpDevelop is the open-source IDE for the .NET platform. Write applications in languages including C#, VB.NET, F#, IronPython and IronRuby, as well as target rich and reach: Windows Forms or WPF, as well as ASP.NET MVC and WCF. It starts from USB drives, supports read-only projects, comes with integrated unit and performance testing tools, Git, NuGet and a lot more features that make you productive as a developer.
monoGIS will be a complete GIS suite for the Mono platform. The current milestone release includes an internet mapserver, OGC WMS implementation and some tools like spatial format conversion. For other projects using monoGIS see mdwglib and Appomattox.