Web application development with WordPress has still not matured, so you will find various perspectives from various people about using WordPress as an application development framework. This section provides various tutorials and articles for understanding various perspectives on using WordPress for web application development:
Wordpress As An Application Platform, Tom McFarlin (http://goo.gl/gONP3i)
WordPress For Application Development, Tom McFarlin (http://goo.gl/ubDasf)
My Thoughts on Building Web Applications with WordPress, Tom McFarlin (http://goo.gl/fTUqQf)
Why WordPress Isn't Viewed as an Application Framework, Tom McFarlin (http://goo.gl/Ophmak)
Using WordPress as a Web Application Framework, Harish Chouhan (http://goo.gl/BFHqVB)
Build Powerful Websites and Applications with WordPress, Piklist (http://goo.gl/WYqRNh)
Build an App With WordPress—The compulsory todo list, Harley Alexander (http://goo.gl/rwMB6c)