Core System Software
GPSD - A GPS Service Daemon - this software was the core GPS monitor and was used by all of the other software that I tested. You need to have this installed and working. Witht GPSD running you can hook in multiple applications and let them all share the same GPS unit. The Linux man pages, gspd(1), let you get access to all the information from your GPS Receiver via Telnet.
List of GPS Software is available here.
I tried out and tested NavIT and GPSDrive and GPSD-Clients.
NavIT was the easiest to use and setup. It hooks into GPSD cleanly. And, you can import maps from OpenStreetMap (OSM) without any issues.
I used NavIT regularly when I was driving around trying to find places.
GPSDrive is nice for watching satellite information and tracking your speed. Setting up the maps is not as easy as NavIT. The interface is also a bit tricky on the smaller laptop screen.
GPSD-Clients is a a set of tools for testing GPSD and making sure the GPS receiver is working. It shows the same information as GPSDrive, but in a simplier interface. The tools include XGPS (GUI) and CGPS (Command Line).