Alrighty guys, I\'m writing an application that I want to be cross-platform. Up until recently I\'ve been trying to do this in Silverlight with C# because it also runs on OS X,
Appart from MoMa as mentioned in the other answers you might be interested in MonoMac. With the success of MonoTouch (writing c# for iPhone), there is now also a project called MonoMac to create native UI's for OSX while using .net/mono in the background. Might be interesting for you http://www.mono-project.com/MonoMac, article on Miguel de Icaza's blog: http://tirania.org/blog/archive/2010/Apr-19.html