I realize a lot of people are big fans of hiding their dock. I find it annoying because there are too many moves instead of darting your eyes. When walking up to a random computer it's worse because I often find those people have moved the dock and I have to check each corner one at a time.
I've had the dock hidden for so long I've almost forgot it existed. I do all my app launching and switching with spotlight and keyboard shortcuts. But just recently I was having a hell of a time locating the trash folder in the filesystem or in a finder window, and thought they might have gotten rid of it or something. Then I remembered the good ol' dock icon.
I wouldn't mind the dock being visible when I'm using my large external monitor, but it just takes up too much space on a 13/15inch screen imo.