Podsights | https://podsights.com | Machine Learning, ML Operations, Software Engineering | Remote within the US | Fulltime Podsights is the operating system for podcast advertising. We likely work with your favorite publisher and handle over 7 billion events a month. Our mission is to grow the podcast industry. Far too many brands try a podcast advertising campaign and churn. Or worse: they don’t even try to... - Source: Hacker News / about 3 years ago

Just did a bit more searching and found this site that seems to have a product, though I'm not sure if it is actively in production and available. Source: over 2 years ago

Jewelry (ring, necklace, bracelet, earring) seems perfect for physical authentication devices: it's easy to carry, always available, and hard to lose. In the middle ages nobles used signet rings to stamp official documents with their unique personal pattern. In modern times, you can stash a Yubikey in a bulky wristband or put it on a necklace chain, but these are not very stylish. There are a variety of "smart... Source: about 3 years ago