Medicine cabinets are great small space solutions since they're shallow and only take up wall space (no big footprint). We can think of a few areas in the home (besides the bathroom) where they'd be useful...
• Use a medicine cabinet in your entryway to hold keys and other small items. A mirrored version lets you check your makeup on the way out the door.
• Hang one over a dresser in the bedroom. Store odds and ends or jewelry inside. A mirrored version works well for this too...it can add a little bit of storage to a spot where you might already be inclined to hang a mirror.
• Hang one or two plain medicine cabinets on a kitchen wall. The depth of the shelves is perfect for spices or small drinking glasses.
• Use a medicine cabinet in a home office to store paperclips and USB cords. Hang a stainless steel version above a desk and use the door as a magnet board (and use this solution from Martha to organize the inside).
Places to find good medicine cabinets: IKEA, Restoration Hardware, or find vintage ones on ebay.
Image: Cartwright Wall-Mount Medicine Cabinet at Restoration Hardware, on sale for $179 - $259