As one of his birthday presents, Oliver got a little wagon (officially, it's called a Toddler Wobbler, which seems prescient) that could be used as a walker. The wheels have adjustable brakes so it doesn't go flying out from under him, and it's just the perfect height for him.
Oliver had it for a week or so and didn't seem to know what to do with it. He put toys into it and pull them out, and sometimes he would push it across the floor with his hand.
Then, suddenly, one night he climbed up, grabbed the back of the wagon...
and he was off, wobbling his way across the living room. We were stunned at how quickly he went, and how eager he was to walk once he figured out how to do it.
He made probably a dozen laps, back and forth, across the living room, stopping only when he hit a wall or another obstruction.
Then his legs started getting wobbly. He still didn't stop. Didn't stop, even when he could no longer stand up and he would push the wagon on his knees. Didn't actually stop until we took him away from the wagon, and he fought us even then.
So now we've got an official toddler. He's compelled to walk now, the same way he was when he first learned to crawl. The urge is so powerful that we have to hide his wagon so he won't just walk back and forth all day. Then he'll just take the laundry basket, or the Incrediblock seem above, and use them as quasi-walkers. To hilarious effect.
Bonus! If you go here, you'll be able to see a very grainy and in-your-face video of the boy walking on his little waddly legs. Enjoy.