Some GPS & Mapping links

Francis Cooke's Garmin essays - Basic stuff:
Living with a Garmin: Etrex Basic Setup
Definition of Terms eg Route, Track etc
Living with a Garmin: Battery Runtime and Etrex Jitter
Living with a Garmin: The Waypoints Limitation (and other limits)
Living with a Garmin: The Follow Road Trap
Living with a Garmin: The Circular Routes Problem
Living with a Garmin: Declutter the Page Sequence
Living with a Garmin: Living with Mapsource Maps
Living with a Garmin: Waypoint Naming (for direct-style routes)
Living with a Garmin: Colour your Tracks and Routes
Living with a Garmin: Create a Route on the GPS
Top 5 GPS Tips (pdf) reprint of Arrivee article published Feb 2007
Some GPS FAQs web version of Arrivee article published Nov 2008
NEW - Garmin Etrex 20/30 essays:
Etrex 30 review reprint of Arrivee article published Jan 2012
Etrex 20 & 30, Basic Setup
Taming the Etrex 20/30: Restore the 'Page' key.
Living with a Garmin: Show on Map (Tracks)
Dakota 20 review reprint of Arrivee article published Feb 2010
Living with a Garmin: Waypoint Naming and the Dakota 20 / Etrex 30
Course Navigation on the Edge 800
by Alan Thompson (external link) 

More Garmin essays - not-so-basic:
Garmin Etrex C Menu Map (pdf, July 2008)
Living with a Garmin: Full Reset
Living with a Garmin: Track, Route or Autoroute
Living with a Garmin: Three Ways to Beat the Waypoint Limit
Living with a Garmin: Three Ways to Beat the Trackpoint Limit
Living with a Garmin: Less is More
Living with a Garmin: Add Contours to your GPS Maps
Living with a Garmin: Struggling with GPX  &...  More GPX
Living with a Garmin: Screens you don't see every day
Living with a Garmin: Downgrade your Mapsource
Living with a Garmin: Put an OSM Map on your Garmin
Living with a Garmin: GPS Soak Test files to test your GPS waypoint capacity
OpenStreetMap and Mapsource Add OSM to your Mapsource collection
A Google Maps Workflow Create, Edit, Save, Share and Export a route
Planning your DIY Perm Route with Google Maps
by Paul Stewart (external link)
Open, Solder, Close an Etrex (external link) 
Online Mapping:
Google Maps
OS Get-a-map
Cloudmade OSM-based variants
OSM Download sites Best most flexible download site, easy but clunky
Freizeitcarte Like the above, but much slicker (Europe only)

Some other useful resources:
Jo Wood's GPS/Audax FAQ - excellent web page, introduction to GPS.
Maps comparison City Navigator and OS Discoverer a must-visit page.
GPS Information .net big resource
GPS Passion big resource
GPS good up-to-date reviews, forum
GPSFileDepot some useful tutorials, forum
Groundspeak Forums GPS-related forum
Open Source GPS How To  ...  Info for Linux users
Garmin  ...   Magellan  ...   Lowrance  ...   Satmap 4 leisure GPS makes
Good tutorials on how the GPS system works:
Wikipedia on GPS
Topografix - the GPX Schema

Desktop Mapping:
Memory Map    ...   Tracklogs    ...   Anquet
OziExplorer    ...   Fugawi
IGN    ...   IGN / Garmin French Basemaps
GPS Turbo open-source, cross-platform, desktop map display

MapSource   ...   and latest version Update (free)
**NB - versions 6.14 or later can be slower in use - see my note here
Metrowizz Autorouting wizard - beats the Metroguide incompatibility trap
Add-on contour maps courtesy of Scottish Mountaineering Club
WinGDB3 utility converts between Mapsource Route/Tracks, useful
MapSetToolKit utility to help add 'other' maps into Mapsource
Garmin latest GPS Firmware Updates (free)
Garmin Communicator browser plugin, connects Garmin GPS
Linux equivalent to above

Mobile Atlas Creator Make offline maps for your smartphone
GMaps Pedometer
Ride with GPS
Optimap quick round-trip solver
EarthTools adds contours to Google mapping
BikeHike uses OS as well as Google mapping
Openrunner uses IGN as well as Google mapping
BikeRouteToaster aimed mainly at Garmin Edge users
CTC Maps good routes resource, parts need CTC membership/login

GPSBabel very good file cleaner and converter, also connects GPS, recommended but geeky!
ITN Converter another converter tool, not so powerful but easier
GPS Visualizer web-based GPS utilities, recommended
GmapToGPX to get GPX from Google Maps
Googlemap Cuesheet to get Cuesheet, GPX and Course from Google Maps
EasyGPS simple clean-up utility, also connects GPS
GSAK (Geocaching Swiss Army Knife) more about waypoints than about routes and tracks
GPS Altitude Chart useful tool, requires Java.
Golden Cheetah very comprehensive tracklog analysis.
RouteConverter planning and converting, requires Java.
Javawa GPS Tools useful conversion, fettling, management tools.
Viking open-source GPS data management
GPS Trackmaker
GPS Utility not free, but very comprehensive