There have been a couple of GPS dataloggers out on the interweb, that cost quite a bit less than the Droid. These are essentially USB dongles that you can power with your receiver battery. You then pull the data off of the logger and can plot it in Google Earth.
Pretty fun stuff.
C
P.S. And of course, since you know your positions and when they were snapshotted, you can always get your speed between them.