My Tracks is awesome. I use it while mountain biking. It keeps track of your speed, mileage, moving/resting time, average time, elevation and other stuff, in real time if you glance at it.
At the end of the race, it can save the track with all the data, and you can upload it to your Google account. It's filed under both My Maps and My Documents for future reference, and you can display all that info on Google Earth as well.
Best of all, ITS FREE. Great app, and very accurate.