Sometimes I find that it's difficult to integrate design elements into a room without that room becoming too "themey." I.e., "the flag room," "the blue room," "the doll room," etc.
Yet if you can find the right piece, and the right room, a bold accessory can seem charming rather than cloying:
My favorite of the above is the star wallpaper on the ceiling in the last image - what should come off as kitsch seems instead well-matched with the minimal walls and bright accents in the room.
Photos from Domino Magazine