My favorite example was Springs. Though it's one of the more mathematically intense examples, it shows that it's still within the scope of p5 to simulate some types of satisfying, realistic motion. Not that realism is the key to everything, or that computer graphics shouldn't look like computer graphics -- it's just fun.
RiTa.js is used for generative text, and has features like a user-customizable lexicon. The projects in the gallery and examples include generated poetry, haikus, and even resumes.
You could use the Cesium Viewer to show geographical data on a map, or maybe in combination with p5.geolocation to display user location. Maybe you see a different aspect of the project depending on where you access it from. You could also use this building block to ask questions about the ethics of tracking user location, and what nefarious purposes this data could be used for.