of those school signs? I know they have a specific name. They're not quite yellow and not quite green. I know, I know - in the scheme of things, this isn't important, but I'm curious.

the fluorescent yellow ones?

yes.

lime?
chartreuse?
fluorescent green?
yellow green?

Fluorescent yellow green according to:
http://www.trafficsign.us/signcolor.html

In CA everything is school bus yellow.

We just have yellow too.

I've never seen any of the green ones the ones up the street from my house are yellow. Just wish the speed demons would not fly down the street at 60MPH, no matter how much you scream at them they just ignore you.

pee yellow/puke green combination

(from the movie American Graffiti!)

In Oregon it is Oregon Duck Yellow, too bad I am a Oregon State Beavers Fan :)