EDIT (February 11th 2012): I uploaded the scripts to github, I hope this way it will never go offline again :-)
EDIT (July 4th 2011): I updated the URL again (here and also added the version with highlighting for .NET keywords. If I have some time I'll try to port it to SD4.
I've been using SharpDevelop a lot in the past couple of weeks and I really like it, it's a hell of a lot lighter than Visual Studio and... it's open source!!
One of the things I was missing was a light-on-dark color scheme, so after a little digging I figured out how and here's what I got:
You can get it from here, just copy the file "CSharp-Mode.xshd" to
"%UserProfile%\Application Data\ICSharpCode\SharpDevelop3.0\modes" and restart