I average 17 to 20, low teens up a hill, high 20s down a smaller hill. If I go into my toughest gear, there's a long stretch of busy road on my way home where I can pump like a mad-man, hit all the lights, make drivers think I'm nuts and hit 35.
Hell, I hit 35mph today in fact.

Road bike, Sora group, steel frame, messenger bag.