Interesting skeuomorphic knobs/buttons that can make the jump from digital to tangible.
A Very Skeuomorphic Switch by Eugene Cheporov
Skeuomorphic - when computer generated graphics are made to look like real life objects
Def. a pro example for good skeuomorphism design. Nice Link > http://sachagreif.com/flat-pixels/
Tracker App - Mobile UI Design - by Tobia Crivellari, via Behance