I did two quick sketches (because computer art isn't quite my medium yet and I wasn't able to work on it at home).
This one is a device that projects what someone is thinking. If you had a cool idea and couldn't verbally explain this would be a useful invention for you, because you could use this device to show people what you are visualizing.
This one shows a futuristic city in the sky where stairs aren't connected, people live in floating pods and when someone walks out their door they will be pulled upward onto a gravity pad.