None of these are anywhere near being anything but rough ideas, but I think they all have merit.
1. An mp3 player, lacking a hard-drive, which, when listened to, automatically generates a real-time 'soundtrack' for the person listening to it by drawing on the soundtracks of every commercially-released film within the past [REDACTED] years. Appears to have mild precognitive properties, as it will play 'suspenseful' music before bad things happen.
2. A 'Stair Snatcher'- a polyp-like organism that grows onto the undersides of stairs in disused stairwells and kills its prey by breaking their ankles and letting them fall to their deaths.
3. Very Soft Pillow: a memory-foam pillow which, when exposed to any smooth, crystalline, inorganic solid, allows its crystalline structure to react as if it were memory foam. This allows one to 'mould' concrete or 'squish' solid metals in impossible ways.
4. Anticlimactic Death Ray. Massive energy weapon, draws huge amounts of power, very dramatic start-up process. Has the ability to make anyone anywhere on the planet slightly sweaty and overheated.
Thoughts? There isn't much detail in my Sandbox, but I'll add more eventually.