Great example, no usable UI
http://blogs.skype.com/devzone/2006/12/c_example_project_for_skype4co.html
Technical Example with some extensions:
http://forum.skype.com/topic/73172-skype4com-c-net-example-full-project/
Visual Studio Express has a Skype API wrapper
http://msdn.microsoft.com/en-us/beginner/aa700775.aspx
SEHE project, I guess it the same as the previous one