X Develop

I've been doing a lot of cross platform .NET develop and struggled with project files and compiling on both sides (Win32 & Linux) between MS's Framework and Mono.

I lucked out and found XDevelop (http://www.omnicore.com/). With built in Unit testing, refactoring, revision control, easy switching between .NET 1.x, 2.0, and Mono, and support for VS.NET's SLN and CSPROJ file formats I found myself in pure bliss...