Glympse is another free app for your smartphone that allows you to share your location with whomever you choose and for how long. If you are meeting someone, they can see your speed and arrival time.
With the price of diesel keeping pace with the price of gold, I am using the GasBuddy App on my Droid X to find the cheapest prices for fuel. Unfortunately, prices change so quickly now days, anything more than one hour old may be out of date.