I'm glad that somebody is finally researching the scientific questions that matter. Witness the following paper on Estimating the Airspeed Velocity of an Unladen Swallow. The anticlimactic answer:

Although a definitive answer would of course require further measurements, published species-wide averages of wing length and body mass, initial Strouhal estimates based on those averages and cross-species comparisons, the Lund wind tunnel study of birds flying at a range of speeds, and revised Strouhal numbers based on that study all lead me to estimate that the average cruising airspeed velocity of an unladen European Swallow is roughly 11 meters per second, or 24 miles an hour.

The fact that I find this amusing probably explains why I've had so much trouble finding a date to my company party. As a famous BBC advertisement for Monty Python once said: "If your girlfriend laughs at this, marry her."