A poll/quiz? You could hand out 9 of them and everyone selects an answer, then the other one shows how many of each answer there were?
You could shove a relay shield on the back of each one and make each one control a small robot
You could stick a Wifi shield onto the back of one, and have it grab data that it sends to all the others (for instance using them as now/next occupancy labels for rooms, or price tags).
You could just do the same but with Node.js on your laptop or a Raspberry Pi to grab the data off the net and put it on Bluetooth.
You could put a bunch of Bluetooth Espruino boards (or just beacons) around and have the Pixl display a map that showed where you are based on which beacon had the strongest signal
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Some stuff that comes to mind...