While working with the Housing and Residences department at the University of Waterloo I also created several PHP-based web applications. The largest of these was a resident profile application, which allowed students to submit their profiles to the site.
One of the challenges the marketing team experienced was a misconception about the experience students would have in certain type of residences (e.g. students thought new, modern single bedrooms in apartment-style units were more attractive, while students in traditional, double-room residences actually had a better experience). This application was intended as a way for incoming students to get a better idea of what it was really like to live in residence.
Another application built for this site was an interactive fee calculator. Adding up the costs of residence and a meal plan can be confusing for students. The fee caulclator used Ajax to instantly display the full costs of different combinations to the students (room type + meal plan type, over 1 or 2 terms).
In addition to these I also built a number of online forms and a simple news update feature. Today I would probably consider using Drupal instead, but at the time writing PHP code by hand was superior to off-the-shelf solutions.