I've been using JogTracker on my Android phone for a few weeks now, and I'm generally impressed with the accuracy and features, especially considering that I am using the free version of this geo-tracking app. I just start a new tracking session, toss my phone in my backpack, and try to remember to stop tracking when finished. It's a big drain on the battery of my HTC phone, but that isn't really surprising (everything is). I like the different modes to select from (walking, cycling, even wheelchair) when you begin a new tracking session, and the interface and companion website are both quite user-friendly. You can easily share tracks and view your history online. You can also export them as GPX or CSV formats containing the GPS data or download a KML file to import into Google Earth. Don't have an Android phone? Try MotionX GPS for iOS. It's not free, but it works very well too.