I have the Holux M-1000c GPS logger. I turn it on in the morning before I go out, put it in my pocket, and forget about it. It logs my position ever 5 seconds while I'm out and about. Battery lasts for a good 16 hours.

I then download my track at night, and use Lightroom map utility to geotag all the photos, automatically. The tracker has held over three weeks worth of daily tracks, with memory to spare. I love it!