Wireless (WiFi + QI charger) real-time temperature display:
QI charger add-ons for mobile phones are readily available for £2-3 from various sellers on eBay and the likes, these make great wireless USB power supplies, they are made of two stickers with electronics and a coil inside.
Peeling back the label reveals all the fun...
I've desoldered the USB cable, you can clearly see the coil on a magnetic backing place, then the small electronics module and at the bottom, three solder pads for the USB connector (the connector mounts a different way up for Android vs iPhone). The PCB is attached to the coil by two wires so can be moved if required, however for now I decided just to attach a couple of power wires and put the charger back together.
Then it simply connects to IO7 +5V and GND inputs to make a completely wireless display.
This could then be mounted in a suitable enclosure, or even encapsulated in epoxy resin (ahtough you'll probably want to get OTA updates working first!).