What was the largest coding project you have ever started with php or other server side scripting languages (I guess javascript counts for the purpose of this discussion too, a well as SQL). Can you also go into specifics about what was involved?

For me it would be my current website which has a custom made guide system. The guides are stored in a database and can be added through a form that only staff can access. I had to learn how to integrate this Site CP with my software, MyBB, by looking at its cooking and allowing content team members and admins to post news posts, manage posted comments on the guides, manage guides, edit guides, and add them.