From GpsWiki

How GPS works

• GPS Tutorial - Trimble
• What is GPS - Garmin
• HowStuffWorks.com
• Wikipedia

How WAAS works

• What is WAAS - Garmin
• Wikipedia

United States Naval Observatory (USNO)

• Block I
• Block II/IIA/IIR/IIR-M
• GPS Constellation Status
• GPS System Description
• GPS Time Transfer Performance
• GPS Timing Data & Information

JAVAD

• Current GNSS Status

Places to purchase the PN-30/40, SD cards, and other Accessories

• J&R Music - PN-40
• Amazon - PN-40
• Wal-Mart - PN-40
• The GPS Store - PN-40
• NewEgg - SDHC
• Zagg - Screen Protector
• MountGuys.com - RAM Mounts
• DeLorme - Accessories
• DeLorme - PN-40

Reviews

• www.gpsreview.net
• www.gpstracklog.com - First Look
• www.gpstracklog.com
• gps.about.com
• chamspage.blogspot.com - (Cham101 on Delorme Forum)
• www.amazon.com
• www.singletracks.com
• www.tripleblaze.com
• moun10bike.workpress.com
• waterfallchasing.blogspot.com

Geocaching

• www.geocaching.com

Forums

• DeLorme
• Groundspeak

Other

• Free Geography Tools
• Navigation Center (U.S. Department of Homeland Sercurity)
• GPS - Serving the World - www.gps.gov
• GPS, Map,. and Compass - USGS Education
• True North, Magnetic North, Compasses, and GPS - USGS
• Magnetic Declination