Guides

Garmin GPS and MapSource Maps - Side-by-Side comparison pages of Garmin's MapSource line of GPS moving map products.
GPS Nuts - Practical guides, tips, tricks, equipment, software reviews, and other related information provided by recreational GPS users.
GPS World - Magazine, buyer's guide, solutions database, columns, products and reviews, and employment opportunities.
Introduction to GPS Applications - Introduction to GPS Applications
Peter Bennett's FTP directory - NMEA-0183 and GPS Information
Sam Wormley's Global Positioning System - Large collection of information/education resources and links, from Iowa State University.