- Access to Camera & Microphone
- Access to USB devices
- Push Notifications
- Geolocation
- Bluetooth
"deep" is probably the subjective term here.
Printer dialogs in browser [_we hates it_].
Access to raw USB devices is a good example I suppose.
Oh sweet. What could possibly go wrong?
Not much, really. Unless the device has been created to work with WebUSB, you first need to manually add a udev rule (on Linux) or replace the driver with WinUSB (on Windows) before you can access it through a browser. Even then, the user needs to select the device from a list, like you would when giving a site access to your camera.
Right, why would we want applications to be able to use hardware anyway?