events

http://stackoverflow.com/questions/550785/c-events-or-an-observer-interface-pros-cons
http://www.codeproject.com/KB/cs/events_and_delegate_in_c_.aspx
http://msdn.microsoft.com/en-us/library/aa645739(v=vs.71).aspx
http://www.techrepublic.com/blog/howdoi/how-do-i-use-threading-to-increase-performance-in-c-part-1/196
http://www.codeproject.com/KB/cs/Cross_thread_Events.aspx
http://www.blackwasp.co.uk/CSharpInterfaceEvents.aspx
http://www.switchonthecode.com/tutorials/csharp-snippet-tutorial-custom-event-handlers