CalypsoCase is an NFC-equipped iPhone case that now lets you literally unlock doors.
Use the case and CalypsoKey, the NFC-powered door hardware by the same company, to make it possible for you to ditch your house keys. This works without a special app and doesn't need to be charged.
You have to bring your own lock to the party, however. The company recommends using Kaba locks.
Pricing on the cases starts at $119. You can learn more about CalypsoKey in this post on the company's blog.
Here's a video of it in action:
Introducing CalypsoKey from CalypsoCrystal on Vimeo.