gpsd is a daemon that listens to a GPS or Loran receiver and translates the positional data into a simplified format that can be more easily used by other programs, like chart plotters. The package comes with a sample client that plots the location of the currently visible GPS satellites (if available) and a speedometer. It can also use DGPS/ip.
GRASS (the Geographic Resources Analysis Support System) is a software raster- and vector-based GIS (Geographic Information System), image processing system, graphics production system, and spatial modeling system. It contains many modules for raster data manipulation, vector data manipulation, rendering images on the monitor or paper, multispectral image geocoding and processing, point data management and general data management. It also has tools for interfacing with digitizers, scanners, and the PostgreSQL, DBF, and ODBC connected databases. GRASS operates on all common operating systems.
Gpsdrive is a map-based navigation system. It displays your position on a zoomable map provided from a NMEA-capable GPS receiver. The maps are autoselected for the best resolution, depending of your position, and the displayed image can be zoomed. Maps can be downloaded from the Internet with one mouse click. The program provides information about speed, direction, bearing, arrival time, actual position, and target position. Speech output is also available.
Quantum GIS (QGIS) is a cross-platform Geographic Information System (GIS). It offers support for vector and raster formats, including spatially enabled tables in PostgreSQL using PostGIS, common GIS vector formats such as Shapefiles, and geo-referenced rasters (TIFF, PNG, and GEOTIFF). Many plugins are available to dynamically add new functionality. Viewing of GRASS layers (vector and raster) is provided by a plugin. GRASS vector layers can be edited in QGIS.
RoadMap is a navigation program for Unix and PocketPC that displays street maps. Most of the maps are provided by the US Census Bureau, and thus only the US has a decent coverage at this time. A specific area can be displayed by entering a street address (street number, street name, city, and state). It interfaces with a GPS receiver through gpsd or the serial line to track the car position. It has been designed to be usable on a Linux desktop or laptop computer, or on a PDA (Linux or PocketPC).
GPSBabel converts waypoint data between about fifty file formats, including Magellan and Garmin serial, Garmin USB, Mapsource, Mapsend, Streets & Trips, Delorme, National Geographic, many PDA formats, and many others. It is endian and word-size safe, includes a GUI, and runs on a variety of operating systems. It also supports Groundspeak GPX extensions for geocaching.
Engauge Digitizer is digitizing software that converts an image showing a graph or map into numbers. The image file can come from a scanner, digital camera, or screenshot. The numbers can be read on the screen, and written or copied to a spreadsheet. Highlights for beginners include an intuitive interface and extensive context-sensitive documentation. Highlights for experts include compensation for image distortion, cartesian and polar coordinates, linear and logarithmic coordinates, automatic scanning, graphical previews, and browser help.
Elgaard Positioning System (EPS) is a moving map application for use with GPS (Global Positioning Systems). It can handle waipoints, routes, and tracks. It can import and export data and communicate with Garmin GPS units. It can use charts scanned from paper charts. A version for the Sharp Zaurus is available.