I only ever visit the Google homepage when someone mentions they have a cool new Doodle. Ctrl-K is how I do all my searching now!
Oh my goodness. I always press ctrl+t and then tab (in FF). I don't know which is better - one is less buttons, one prepares a new tab (with some leet ctrl+t, ctrl+tab, ctrl+w, tab, I can achieve the same as ctrl+k...)