Me too. Underlined links, or more precisely, links that don't obey the browser's Underline links setting (which I set to "Hover", btw) are my pet usability peeve because I have difficult reading underlined text.

Bill's right, by the way. Underlining came about because it wasn't feasible to put italics on a typewriter, and two spaces after periods came about because typewriters only had one size "space", and thus, couldn't duplicate an "em" space.