[WordPress] Custom Functionality Plugin for WordPress

Why and How to Create Custom Functionality WordPress Plugin
http://www.onextrapixel.com/2012/06/26/custom-functionality-plugin-for-wordpress-pros-and-cons/

Discussion on WordPress MVC Compliance
http://stackoverflow.com/questions/2857143/is-wordpress-mvc-compliant

MVC Framework Plugin for WordPress
http://wpmvc.org/