GPS

Here is my personal resources on getting opensource/communities made map and install into GPSr.

http://nzopengps.org/
http://www.mapsntrails.com/en
http://mobac.sourceforge.net/
http://www.osmaustralia.org/
http://thebikegeek.blogspot.com/2011/06/downloading-open-source-maps-for-garmin.html
http://gpsinindia.com/
http://gpsunderground.com
http://garmin.openstreetmap.nl/
http://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/Download
http://gpsmapsearch.com/
http://www.topomapper.com/
http://www.gpstravelmaps.com
http://bikeroutetoaster.com/

And here is a collection of website that allow you to share your GPS track online
Everytrail
Garmin Connect
Map My Ride
Strava
Endomondo (work with smartphone only)

In-depth knowledge on GPS & related stuff
GPS Maps Wiki