This one definitely falls under the 'want' category rather than the 'need' category, but it might be just the ticket for riders like myself who are unashamed gear dorks. Hutchinson's 'Connect Tires' is a real-time pressure monitoring system for road and mountain use that, thanks to Bluetooth and ANT+ compatibility, can tell your phone, smart watch, or GPS unit exactly what's happening with your air pressure.
The unit pictured here is a prototype, with the production version being encased in a waterproof housing that your tubeless valve passes right through to hold it in place, and the whole thing sits down in the rim bed. Most interestingly, the Connect Tires works with both tube and tubeless setups thanks to dual pressure-measuring systems. If you run tubes you should stop doing that, but if you insist on using tubes, a load sensor measures exactly how hard the tube is pushing down on it and it can determine your air pressure from there.
The sensor on the left measures the load applied from a tube, while the small hole on the right works with a tubeless setup.
If you're running a tubeless setup, a tiny hole on the unit leads to a piezoelectric sensor that constantly measures your tire pressure. The hole is quite small and looks like it might clog with sealant, but Hutchinson is insistent that they've had no issues during testing with both fresh and dried up tire sealant, and that it'll play nice with any sealant on the market.
The unit, which weighs just 10-grams and is compatible with any rim, talks to your phone through an app that you can configure a few different ways. If you're using it on a mountain bike, you'd probably want to set it up to make an audible warning sound if your tire pressure dips below, say, 20 PSI. But if you were using it on a road bike, you can set it up to warn you at a much higher pressure.
It might also be useful if you're the kinda gear dork who wouldn't mind keeping track of what tire pressures work best on certain trails or conditions, and you'd be able to keep tabs on that by simply opening the app. It'll even give you pressure recommendations, too.
Hutchinson doesn't have an exact price at this point but expect it to come in somewhere around $100 USD.