Julie, Zapotee -- thanks for the tea tree oil instructions. I might give it a whirl after we get rid of everything for certain. I even quite like the smell (in small doses!).
Laura, I'm very interested in this new product you describe. I'll be asking the pharmacist about it next time we're in.
Louise, no I don't colour my hair anymore, I've grown quite fond of my natural hair colour...but I do often use a blow dryer, sometimes a flatiron, and almost always some hairspray (even if I don't do rock n' roll hair). I'm sure all those things help keep lice at bay, although are probably not foolproof.
Donna, yep you're right. Not only do they share hats and stuff, but at school they all hang up their bulky winter coats right next to each other, so I'm sure there's some transfer that way.
Haven't found any lice at all for five days! Still finding the odd nit. I hope I get all of 'em eventually...