I currently use a Holux M241, and the features I like most are
However, the memory for 131000 track points (less with newer firmware) is a bit tiny for any holiday of more than a week.
I found the "Locosys GPS Walker" with about 2 GBytes of Memory (and a built-in mp3-player, who needs that?), but that thing has some disadvantages:
When you want to know where you've been using GPS, you basically have two options: active tracking and passive tracking.
Passive tracking is what most users of this site are doing: an electronic devices stores the positions internally and these positions are recovered at a later time.
Active tracking generally implies the transmission of the current position to some kind of server in "real time". And that is most of the time done using the GSM/GPRS network.
When I discovered about 'Kookoo', the tracked cat back in May, I had no idea that I was going to work on a project to track dogs. And yet, I did.
It is fascinating how someone puts so much effort and time into such a nice piece of software. I'm no programmer myself, but I did work in software testing some time ago, so I will try to help as best as I can.
My picture shows Ping, who likes to show me the way (sitting on a map). Holly (not shown, my Holux M241) later tells me where I actually was. Ping ususally disagrees ...
GPSLog Labs is another site where you can store your tracks that is well worth a visit. It analyses your track to find positions where you stopped and splits the track in several subsections.
The site is pretty responsive too.
I added this to the list of sites where you can share your tracks.