I really enjoy the more complex development project. I had the honor of developing the Vexilar University, an online sales training system. Sales professionals create an account, then go through a series of courses. They watch a video and then take a short quiz. If they pass all of the video courses, they graduate. The system was designed as a mobile-first application, with ample reporting for Vexilar to show how the system is being used.
Simple File List is my Full-Featured WordPress Plugin Providing You a Fully Configurable File List and Optional File Uploader.