Minecraft wiki entry for Item_Frame, associated text: Original Reddit image suggesting item frames and flower pots.
Dinnerbone's first screenshot showing armor and weapons.
Dinnerbone's second screenshot showing a map, a compass, and two diamond swords.
Dinnerbone's third screenshot showing a golden sword in all directions, the item frame item itself, and a working clock.
Jeb's screenshot of the item frame.
Snapshot showing plant pots and item frames.
Snapshot image of an ender pearl in an item frame.
An image of a fireplace retweeted by Dinnerbone.
An image tweeted by Dinnerbone showing how hovering over an item frame containing a renamed item shows a name tag.