flocking navigation system for airplanes (to save on fuel)
hybrid hot water heater - pre-heats water to ambient temperature in an uninsulated water tank and then heats the rest of the way on demand with a tank-less water heater (someone told me that already have such a system at their cottage)
electro-magnetic transmission using Ferrofluids. The magnetic forces wouldn't need to be strong enough to hold the gears, mearly strong enough to harden a thin film of Ferrofluids (liquid magnets which become solid when exposed to a magnetic field) in order to make a physical connection. If the gears where cone shaped and running along side each other in opposite directions then you could probably make a continuous differential gearing system by controller where you create or aim the magnetic field.
cell-phone cradel for providing land-line like service to POTS phones already done
SAM - Sequential Access Memory - ideal for MP3 players
sculptable keyboard with movable RFID keys (and other components)
gene-spliced "cornucopia tree" which bears multiple species of fruit (and many "vegetables" like tomatoes and peppers which are also actually fruit)
spherical robot with no moving parts - driven by controlled activation of electromagnets lining the inside of the sphere - only works on metal surfaces
fuzzy micropayment system makes small payments viable by using probabilistic money (others came up with this idea first)
a computer mouse which remaps my keyboard layout when it detects that I have my hand on it. When using my mouse with my dominant hand my keyboard would be remapped into "mouse mode" where the keys under and around my non-dominant hand would change to things like: arrow keys, delete, backspace, tab, cut, copy, paste, home, end, page-up, page-down, etc.
RF shielding on the inside of my clothing pockets so that when I cary around things like cellphones I'm not radiating myself. related