A units of measurement converter. Think about all the things that are measured, like distance, area, volume, energy, weight, temperature, pressure and so on. Now think about the many units of measurement the people around the globe use, anything from rods, stones, pounds, inches, pints and liters. A rather long list.

Start simple, let's say just the distances and a few units. Get that to work, then add more. Google the net for conversion factors. How would you handle the information? Maybe a dictionary in Python. Are there any neat shortcuts?

Your program should answer questions like:
"How many inches in a meter?"
"How many milliliters in a pint?"
"How many acres in a square-mile?"
"How many pounds in a metric ton?"
"How many calories in a BTU?"