developer payment gateway – https://stripe.com/

Understanding the PHP object model – http://www.slideshare.net/sebastian_bergmann/understanding-the-php-object-model

http://net.tutsplus.com/tutorials/php/zend-framework-from-scratch-models-and-integrating-doctrine-orm/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+nettuts+%28Nettuts+%29&utm_content=FaceBook

https://build.phonegap.com/

http://stackoverflow.com/questions/61401/hidden-features-of-php/

http://stackoverflow.com/questions/1170338/mercurial-for-beginners-the-definitive-practical-guide

http://www.databaseanswers.org/data_models/index.htm – data model collections

http://martinfowler.com/eaaDev – development blog and best practices by martin fowler

http://orm-designer.com

http://gocartdv.com/ – codeigniter based cart