As far as i could remember, I have always been using Eclipse + Improve C# Plugin + Mono to develop .Net apps in Linux.
But this caught my eyes today. Its a plugin called Grasshopper developed by the guys from Mainsoft that you could use to help you develop .Net apps in Linux. Here is a description i got from their website:
"Grasshopper, the Developer edition of Visual MainWin® for J2EE™, is a Visual Studio .NET® plug-in, which enables you to use C# or Visual Basic .NET® to develop, debug and deploy Web applications and Web services that run on Microsoft® Windows®, Linux® and any Java™-enabled platform. Grasshopper supports single-source code development, so you can develop an ASP.NET application that will compile and run on multiple platforms. Grasshopper bundles the Apache Tomcat application server and PostgreSQL database, so you get a complete cross-platform Visual Studio development environment for any platform running Apache Tomcat."
This is something that is really interesting infact im going to try it today since they have a developer version that you could readily download at no extra cost! I have been reading alot of reviews about it and it seems to be a really good tool. I'll report to you my findings as soon as I can.