User Messaging

[eluser]austintbiggs[/eluser]
I'm currently attempting to build a messaging system for use between users. And I was wondering are there any examples out there? Has anyone already started or developed one? I've done quite a bit of googling, but the results I got were all regarding error messages.

Also do I use emails or another method? I'm still trying to develop the concept of how it would work so I can start programming.

Any and all help is appreciated!

Best Regards,
Austin.