When we go geocaching we have a couple of different GPS options depending upon which
vehicle we take.

TomTom One 3rd Edition

Mio Moov 200

Garmin 12 (no mapping)

Once we are out of the car we use an old Garmin 12. It is probably 10+ years old.
It is as basic a GPS as you can get with no mapping and no USB interface.

I am working on getting geocache locations loaded into all of the platforms so that
when we are out and about running around we can see all of the local caches and then
stop for a quick hunt if we have a little bit of time.

Here is an interesting solution for getting the locations imported as POI (Points
of Interest) into the TomTom. This will be a hack that I going to try as it looks
pretty simple.

http://www.bioneural.net/2006/01/13/geocaching-with-tomtom-a-solution-for-mac-palm/

Another option is using http://www.gpsvisualizer.com/gpsbabel/ to
import and export the files over the web. It looks like it supports all of the formats
that I will need.

A couple of the better software packages:

Geocaching Swiss Army Knife http://gsak.net/

GPS Babek http://www.gpsbabel.org/

Nice Geo calculator:

http://www.gpsvisualizer.com/calculators