I did the read the encyclopedia thing, too. Glad to know I'm not the only one. I blame that on my parents always telling me to "look it up". After a while I was reading it for fun. Guess my parents go their money's worth out of that set. I also loved reading through the sets of books on American History and Science they bought for us. Another favorite read was a collection of myths and legends. My earliest nerd moment was wondering why the Thor in the comics wasn't like the Thor in the myths. I was big reader, always getting gold stars for that in school. Once I even checked out the book the teacher was reading to us, because it was taking too long. Now I have to read, its like an addiction. I read, billboards, road signs, cereal boxes, bumper stickers. Anything with words on it that's in eyesight. Also, I tend to comment on what I read, which drives the wife crazy.
Art was another nerd thing. I was always drawing. Superheroes were a favorite subject and I started making my own comics. I still have a drawing pad in my car and will draw at lunch when the mood strikes.
I sucked at sports, too. Funny that I had the eye hand coordination to draw but not to throw a ball. The only sport I was decent in was swimming. That was the result of watching too many movies where Tarzan fought crocodiles.
Oh yeah, and I watched a lot of Star Trek.