iPhone app that automatically keeps track of your commute and helps you detect patterns. Using geo-fencing, it could keep track of when you leave your designed home/work spots, and then do a continuous GPS track along the way. Once data is gathered, it could be visualized (e.g. by day of week, or by departure time), displayed on a map to show alternate route rates (e.g. Grant Road vs. 85) and with enough smarts, turned into a (local) push notification that tells you which way to go today.
Commute Tracker gets pretty close to this (it's automatic), but it's buggy (I had a 1 second commute), tracks too much (I want to exclude days where I make a grocery store detour) and is on the ugly side. Daily Commute is prettier, but it's too manual, requiring commutes to be started and stopped.