The Team Oregon Pace Wizard is a must have effort based training tool for serious distance runners and coaches. It is particularly useful for training and racing using a heart rate monitor. This free version lacks all the features of the paid version.
Key features:
 - Predicts road race times, paces and heart rates for   distances from 2 miles to a Marathon
 - Computes proper endurance training paces and heart rates
 - Handles English and Metric units
This tool is used by Team Oregon for coaching beginning to elite athletes. This mobile version is handy at the track or on the road.