I am a reasonably good typist, and learned on manual typewriters, but since I've been using PC keyboards that's one thing I've never figured out how to do. And, that is; how do you underline your words while you're typing them? You cannot do it later, like in a standard typewriter, and I see no way of doing it "as" you type. So how??
Thanks.
I'm afraid the first 3 answers do NOT work. I need to do it when I'm typing an email or info on a website.

right before you type the word, hit control+u. right after the word, even before you hit the space bar, hit control+u again.

same applies for bold: control+b
and italic: control+i