I was at Toys R Us a few days ago, looking for toys and picked one of these up on a whim (a Subaru Impreza).
I have to say, these things are wonderfully addicting, and for what they are, they work incredibly well! Everything is small enough to fit in your pocket, but these little things actually pack quite a punch. They even have intechangeable motors, gears, tires and bodies, for whatever suits your racing needs. Wonderfully complex little gadgets, and they only run about $20.00 for the remote and a complete car!
Even cooler, the company that makes them also has the liscence for a couple of my favorite racing games: Auto Modellista for PS2 and Mario Kart!
For Auto Modellista, they have kits with a remote, 1 chassis and 4 bodies with A.M. artwork. The Mario Kart sets are incredibly cool, including a remote, either Mario or Yoshi on their go cart, and little items from the game, like turtle shells, banana peels and mushrooms.
I'd definately recomend them to anyone, adults and kids alike. They are small enough to keep anywhere, charge very quickly (45 seconds), each charge lasts quite a while (depending on which type of motor you use), anywhere from 5-20 minutes. Something fun to just get out on a whim, play with to pass the time, and put away again.