Being from Oregon, and living in California, I tend to get all mopey when confronted with the unrelenting good weather down here. Magic Vision Lab has designed an augmented virtual reality system that's capable of turning any nice day into the wet and dreary wretchedness that I miss so much.
This VR system looks to consist of an immersive video display with a head tracking sensor, calibrated so that what you see when you move your head is exactly the same as what you'd see if you were just looking around with nothing on. Software senses the ground and the sky, and then adds sound and graphics of snow, rain, or hail, complete with realistic particle interactions with the ground.
It's definitely a convincing piece of gear, but as Make quite rightly points out, this system suffers from a serious lack of snowblowers, water cannons, tesla coils, and flash-bang grenades to really drive home the bad weather experience.