Ultra-precise altitude
Altitude measurements are taken from the USGS National Elevation Dataset, which is the most precise and accurate dataset available for North America. (In particular, it beats GPS calculations, the google elevation api, and all but the best barometers.) This precision is essential for calculating cumulative elevation gains along a route, where small errors are magnified with each new datapoint.
Know the hills before you ride them
Plot a route and head out for a ride. The app will tell you when a hill is coming up, and will even tell you how steep it is and how far you are from the top. Customizable to give you as mush foreknowledge as you can bear, and always a little more than your friends.
Future Concepts
When used with a stem-mounted smartphone, the phone's back camera will watch you pedal and report back cadence-- no more crankarm magnets.
Point your phone's top camera forward with the available periscopic phone case, and turn your smarthone into a GoPro.