a hinged full length mirror from IKEA (Stave mirror - that is x hides jewelry storage -- brilliant idea from The Girl on the Go! I would use a thin sheet of plywood cut to fit behind the mirror so I don't put so many holes in the wall.
Utilize space between studs to add shelving. This would be ideal down a long hallway. Add glass shelves and lighting for display or cabinet doors to hide stored items. Install adjustable shelves to allow for easy changes.