Seeing as it's my birthday today (Go 14!) I got a remote control helicoper (damn good present, too) I remembered seeing something about a remote control tank. So I looked it up and found it.
This guy in Sweden has put together a remote control M5 Start Model with a webcam on it. There is a laser targetter, Laser Target Shooter and a paintball gun (But of course he wouldn't trust me with that

)
So using ActiveX and IE, he allows you to see what the tank sees, move it, aim the gun and fire. He's happy to just let you have a go on it.
He says it cost about ?1500 to build, and I do believe him. He also says he has plans for an army of these, and multiplayer laser/painball games. Sounds fun!
Anyway, Driving a remote control vehicle is fun, A model tank in Sweden in someones house is just great!
Contact him using his msn:
spidg@hotmail.com
As for lag, there isn't too much, maybe a second or so. Decent webcam, too. Not one of those near black-and-white ones which updates every 30 seconds
So, overall, a very fun experience. Must build myself a life-size version with SABOTs one day..
Have Fun!