Paceband Mobile is the swiss army knife of running apps. It comes with a GPS enabled stopwatch that saves your runs to a database so you can review them and share them with friends via Facebook. It also has a three way split calculator that can calculate finish time, distance, or pace by supplying any two values. It also has a calculator to predict finish times. Simply supply your best recent finish time of any distance and see what you are capable of doing in virtually every event from 100m to 100 miles.
The application works in miles or kilometers. You can also configure your body weight in pounds or kilograms (required for calorie burning calculations).
Note: Continued use of GPS running in the background can dramatically decrease battery life.