~£60 on eBay: http://www.foscam.com/Products_List.asp?id=128 This may be ANother security camera idea reply for this post, but I have to agree the idea's a good one. It can be left on permanently and constantly streaming. Buy one for both parties and then each can move the camera around to follow what the other is doing and feel much more a part of the scene. It even claims to have a microphone and speaker for talking, but I've not managed to make mine work. Perhaps a more expensive version would be easier to use, although I'm happy with mine. Leave a low powered computer and a low powered screen constantly showing the stream, or maybe you can get the motion detection feature to work on the one I've suggested and set that to wake the screen up whenever it detects you're in front of it. If you can get it to wake the screen then you can probably get it to run a batch script and auto-start a skype conversation. In fact, it sounds like you need a motion detector and a simple web cam with skype at both ends. The only trick is to get the motion detector to wake the computers in both locations. Surely someone here knows how to do that? Good luck!

You're not stupid: IN A STEADY STATE, going truly downwind, taking power out of the vehicle (hence reducing its kinetic energy) by applying a torque on the wheels to speed up the propeller will slow the vehicle down. Using that power (assuming none is lost internally) to do work on the apparent wind to speed up the vehicle can only ever add kinetic energy at the rate at which it is taken away by the friction on the wheels, and hence it will only ever maintain the current speed, it's like putting a turbine on the front of your boat to power the propeller at the back. Also, if you travel faster than the wind speed then there's a drag that you have to do work on, and if there's no power being gained (which there can't be, because the propeller is doing work, not gaining it) then the car cannot maintain a steady state speed greater than the the wind speed. The article and videos make no demonstration that the brief faster-than-wind speed can be maintained.

Think of it another way, if you look at the whole contraption and it's travelling faster than the wind speed, then you start driving along side it at the same speed as the wind, you're now looking at it in a moving frame of reference. It appears to be moving into stationary wind at a constant speed, and it can't possibly do that forever because there will be a drag force on it, however small, that will dissipate its kinetic energy and slow it back down.