Cross process communication

Question

I am writing an application and need to send messages back and forth to different applications.  What is the best way to do this?  The simple example would be if you have two simple GUIs.  I want GUI-A to send a message to GUI-B and have GUI-B display what that message is.  Kind of like a chat.  In reality I need GUI-B to do a bunch of stuff based on that message but that is unimportant for this question.   The messages only need t send to other app on the same machine so a web service is not appropriate.  The only examples I could find on remoting basically just instantiate remote object on some other system and pass back a result.  I found some other stuff on named pipes but don't understand those too well.  Please help me understand what technoloty I should use.  I can do my own research on the code if need be, just looking for some direction.  Thanks!!!