Powered Item Frames

You can already read the rotation of an item fram with a comparitor - feeding that same power level into a second item frame would make its rotation match the first. (But usually you'd power it from something else) This could be used by a veriaty of contraptions, such as gauges, pointers, alternative clocks, puzzel games, arty animations (I'm thinking googly eyes would be asuming). ​ Taking this further, maybe fully powing it would lock it to its current rotation - stopping accidental rotation, or locking it in a selection after a user has rotated it.