Growing up, I was a huge fan of remote control cars (I assume I would have been a huge fan of RC planes and helicopters and boats too, I just never owned any so I can't say for certain). There is something excellent about holding a remote in your hand and watching this thing that's 20 feet in front of you race off and turn and crash at your command.
Of course, technology improves – gadgets get better. The RC car, presumably, isn't going anywhere, but if you're in your 20s or 30s it might not look quite so cool for you to be going around your block racing one. Enter Sphero. Sphero is a little white ball with something inside (let's call it "magic") it that allows it to spin on your command… using your smartphone. All you do is connect the Sphero to your phone/tablet (iOS or Android) via Bluetooth and then open one of the multitude of Sphero apps and race that little white ball with the potential to be oh-so-many colors via LED lights.
Okay, the boring tech bits before we get to the fun (and, in case you couldn't tell, Sphero is fun). According to the website, Sphero is a "high-impact polycarbonate shell" weighing 168 grams and with a 74mm diameter. In English, it's plastic-y, fits comfortably in your hand, and isn't too heavy. As for that "magic" that makes it move, that's attributable to its "multi-axis rate gyro and accelerometer." The whole thing works off of lithium polymer batteries and can run for about an hour on a four hour charge.
Yes, that charge bit is less than awesome, but you know how cats go crazy for laser pointers? Sphero does the same thing to toddlers.
It says on the box to not let anyone under 13 play with Sphero, but in our world that means that no one under 13 gets to touch Sphero or the iPhone which controls it – those under 13 (like the 19 month old) can feel free to run after it to their hearts' content… or until Sphero needs to be charged again (the latter is more likely than the former).