When I took typing (one term, back in grade 11, and I'm really slow) they taught me two spaces. And when I type on a typewriter (BTW, can't remember when the last time I did *that* - typewriters are so... so... passe?) I do use two. I also use two if I'm typing up something formal, like a job cover letter or something like that where you might have a picky reader. But in email and fanfic and other less formal instances, I use just one. Saves time and space, and in places where they count every keystroke and limit you to a certain number, it's a real lifesaver...
Melisma (under her Rock, admitting - with red face - that she has joined at least one singles' dating site that limits comments and emails to 5000 characters per response box, and IMs to just 200. The one-space habit makes LOTS of sense with them!)
