The following are links to other software and websites which have some relation to GPS systems, coordinates, mapping, exif and other good stuff. A mention here isn't necessarily a recommendation, but a starting point. Most of the software here is gratis, free and open source, and these are marked with the symbol (free). Some are gratis but closed-source, and some require payment to work properly.
These are applications for editing, viewing or converting coordinate data from GPS receivers. Most of these, like Prune, concentrate on manipulating the data after it has been recorded, rather than working with live data.
(free) Specialises in conversion of coordinate data between file formats and data formats. Can be run either from the command line or from a GUI.
Runs on Linux, Mac and Windows. Source code available.
Wikipedia page en.wikipedia.org/wiki/Gpsbabel, home page gpsbabel.org.
(free) Linux program to automatically correlate photos with gps tracks (in GPX format) using timestamps. It's similar to Prune's autocorrelate function. Can be run from the command line or using a gui called gpscorrelate-gui.
Minimal information can be found in these online man pages.
(free) Linux program to extract data from Garmin GPS receivers. Command line only.
Cross platform, written in C. Source code available.
Sourceforge page is at sourceforge.net/projects/garble.
(free) Java program for conversion and manipulation of GPS data, including photo correlation. Command line only. Source code available.
Sourceforge page is at gpstools.sourceforge.net.
(free) Popular KDE-based photo management application, including powerful tagging system. One recently-added feature is geolocation of photos, with a Google Maps interface for specifying the location of a photo, and an automatic correlation function using a GPX track.
Currently Linux only. Source code available.
Wikipedia page en.wikipedia.org/wiki/Digikam, home page is digikam.org.
Powerful 3d visualization program, with layered view, spectacular terrain data and even a built-in basic flight simulator. Allows easy overlay of GPS data using KML or KMZ format. Prune can export to both these formats, including photo thumbnails if available.
Closed source, but gratis and available for Linux, Mac and Windows.
Wikipedia page is at en.wikipedia.org/wiki/Google_Earth, home page is earth.google.com.
Powerful 3d visualization program oriented towards scientific data presentation. Currently Windows-only, but plans exist for future cross-platform versions.
Wikipedia page en.wikipedia.org/wiki/NASA_World_Wind, home page worldwind.arc.nasa.gov.
(free) Command line, python-based tool for correlating photos with GPS data (in GPX format) and saving the coordinates in Exif or in a KMZ file for Google Earth. Should be cross-platform, but only tested on Linux. Source code available.
Sourceforge page happycamel.sourceforge.net.
(free) Linux-based software for navigation using zoomable maps. Has the ability to read current position from the GPS receiver using NMEA, and includes a version of Garble for accessing stored data. Source code available.
Wikipedia page en.wikipedia.org/wiki/GpsDrive, home page gpsdrive.de.
(free) Command line perl tool for automatically correlating photos with GPS data (in GPX format). Runs on Linux, Mac and Windows. Source code available.
Sourceforge page sourceforge.net/projects/gps2photo/, home page www.carto.net/projects/photoTools/gpsPhoto.
(free) Java GUI tool for converting coordinates between a host of formats (including gpx and kml) and using a nice Google Maps interface to display them. Runs on Linux, Mac and Windows, with GPL'd source code available.
Home page routeconverter.de.
(free) Command line java tool for automatically correlating photos with a GPX track and writing the coordinates to Exif. Doesn't rely on Exiftool to do the writing. Development appears frozen at release candidate stage, with no future releases planned. Should be cross-platform, described as "open soorce" (sic). Home page at wiki.hsr.ch (suspended).
(free) Comprehensive GIS tool with some GPS-related functionality, including downloading data from GPS receivers using Gpsbabel and overlaying on other geographical data. Also loads delimited text files and Gpx files. Runs on Linux, Mac and Windows. Source code available.
Wikipedia page en.wikipedia.org/wiki/Quantum_GIS, home page qgis.org.
Closed-source, Windows-only program for downloading data from Garmin and Magellan GPS receivers, and editing and charting the data. Limited functions until purchased for EUR30.
Home page gartrip.de.
Closed source, Windows-only, costs $40. Provides photo correlation and some data conversion options. Home page robogeo.com.
Closed source, Windows-only, gratis. Only does photo correlation, using NMEA, GPX or with a Google maps interface. Uses Exiftool to save the coordinates in the pictures. Home page geosetter.de.
Closed source, Mac-only, costs 25 EUR. Only does photo correlation, either using a GPX file or with a Google maps interface. Home page houdah.com.
Closed source, java, donation requested. Only does charts of altitude either against time or distance from GPX files. Home page 2steger.de/gac.
Closed source, Windows-only, gratis / 35 EUR. The gratis "easy" version apparently just does data transfer to/from GPS receivers, the paid-for "expert" program offers mapping, elevation charts and data editing functions. Home page topografix.com.
Closed source, Windows-only, gratis for personal use. An impressive list of features including track editing, 2d and 3d charting, photo correlation, and analysis. Seems to be only in German. Home page gps-freeware.de.
These utilities aren't directly related to GPS but can be used in conjunction with GPS software.
(free) Java library of functions by Drew Noakes to allow programs to extract metadata from for example Exif blocks in Jpeg images. Used by Prune to read timestamps, GPS coordinates and thumbnails from photos. Source code available.
Home page drewnoakes.com/code/exif.
(free) Command line perl tool for reading and writing metadata in for example photo files. Called externally by Prune (if it's available) to write coordinates in the Jpegs. Runs on Linux, Mac and Windows. Source code available.
Home page sno.phy.queensu.ca/~phil/exiftool.
These are programs not necessarily related to GPS systems but general 3d modelling and rendering programs.
(free) The granddaddy of 3d rendering software, a gratis cross-platform ray-tracing program. Prune can output models in .pov file format for rendering by Povray. It has a host of rendering configuration options, and can be run from the command line or from a Gui.
Runs on Linux, Mac and Windows. Source code available.
Wikipedia page en.wikipedia.org/wiki/Povray, home page povray.org.
(free) Povclipse is an eclipse plugin to make editing of pov models easier. However I was never able to get it to work properly.
Runs inside eclipse, so cross-platform.
Sourceforge page povclipse.sourceforge.net.
(free) KPovModeler is a modelling program for creating and editing pov models. Again I was never able to really get this to work properly or get it to understand the pov models from Prune.
Runs on KDE, which means (for now) Linux-only.
Home page kpovmodeler.org.
These are websites related to mapping, geotagged photos and GPS plotting.
The well-known maps.google.com has worldwide coverage and a fast, draggable interface. Also includes search functions, overlay of KML or KMZ files, and even driving directions. Zooming in brings further information such as tram times.
A Swiss-specific map site, map.search.ch, has excellent local information including train times, hotels and so on, and a smooth zoom function. Some of the data (eg for Vallorbe) is broken.
The ambitious free mapping project at openstreetmap.org aims to provide free worldwide maps based on volunteer data. Coverage is much lower than the commercial offerings, but growing, and can be used without restriction.
The popular photo-sharing site flickr.com includes geotagging of photos, and a simple interface for assigning coordinates to photos. Requires user registration.
Another photo-sharing site locr.com concentrates on the idea of geotagging photos (rather than that being an optional extra). Requires user registration to submit photos but anyone can browse using the map.
Available as a data overlay in Google Earth, photos from panoramio.com are tagged (sometimes incorrectly) with coordinate information, and appear when browsing around an area. Corrections can be suggested using a Google Maps interface.
gpsdrawing.com is a project to make pictures using GPS data, for example the famous "Brighton elephant". The gallery is particularly impressive.
Actually this should probably be listed under "software" rather than "websites" - it's an impressive set of utilities for conversion and manipulation of data at gpsvisualizer.com. With it you can upload data and generate maps, kml files and other plots.