What a great thread! I wish I could meet all of your kids--they sound wonderful!

Some of my favourite Harpo (now 7) moments:

When he was 2 and just starting to read aloud to us, he'd also spend a long time quietly staring at print of any sort (cereal boxes, whatever). One day, he asked me to type him two pages on the computer, one with lower-case "a" in every font, and one with lower-case "g" in every font. I thought this was a little odd, but I did it, and he carried it around like a talisman for weeks at a time. I finally figured out (I am slow) that those are the only two letters that exist in two different forms, according to font. So then I went up to the university library and got a bunch of books about type design, and he was in hog heaven for months.

When he was three, he'd lie on his bed for more than an hour at a go for about a week, chanting the alphabet slowly to himself. At the end of the week, he came down and said, "there are only five letters where I don't have to do anything with my lips or my teeth, and they are a, e, i, o, and u." Then he went happily out to play.

When he was four, we were waiting in a long line at the bank one day, and to keep him happy, I handed him a bunch of the bank's pamphlets about their services. One of them had to do with the bank's commitment to keeping its customers' personal information confidential, and had a photo on the front of a woman locking up a huge safe. He looked at it for a while and said he'd like to see this safe, where was it? I explained that there wasn't really a safe exactly like that particular one, but that they were trying to get across to people how seriously they took their privacy concerns. He said, "Oh, you mean it's a metaphor?" Every adult head in line snapped back in our direction.

Sorry, too many stories--I have pent-up bragging needs, since I only have one person I can tell this kind of stuff!