OS X - Adjust the volume in 1/4 increments with shift+alt+volume keys.
/via GDmac
iOS 6 - When turning the volume up with headphones connected, the volume bar shows warning indicators in yellow and red.
/ via frietman
OSX - When unplugging your headphones from a Mac, it automatically reverts to the most recent volume settings of the new output device.
IMDb - The rating for ‘This is Spinal Tap’ goes up to 11
/via treitmaier
Vimeo - The bar you mouse over will grow taller so you known when to click.
/via Patrick M. Lozeau
BBC Radio 1 - The video player volume control goes up to 11.
/via Abhimanyu
Mac OS X - Pressing Alt ⌥ and clicking the volume icon lets you select input and output device.
/via jage