MonoDevelop isn't bad software. It has a few languages supported, like C++ and C#. It might be useful to use. For creating games? Irrlicht has Linux support iirc, I don't know if there's any tutorials for setting it up in MonoDevelop, should you struggle, I am sure there's alternative C++ IDEs. 3D Software, Wings3D and Blender seem to be the choices. If you prefer C#, I don't know if it's possible to get Irrlicht lime or Irrlicht.NET to run in Linux.
Unity3D 4.0 will have Linux support, however, I believe it'll build to Linux but not develop on Linux, but then before there was a PC version, the Mac version let you build to Windows, but not develop on Windows, so there might be hope in the future.