Today, probably 20-ish on my commute to campus. That's typical on my daily rides.
Last week riding with my boss I hit 37.2 MPH doing an aero tuck on a nice section of hill north of town.
My all-time record is 38.something, going down a hill and pedaling like mad. I might be able to beat that if I swap out my gearing -- my smallest cog is 14 teeth.