Tutorials

ESRI Training
ArcGIS 10 training, lots of podcasts and on-line classes to come. Most of the training is free.
ArcGIS Tutorials
A set of links to a collection of various ArcGIS tutorials used to perform a number of common tasks in ArcGIS.

How GPS Receivers Work
Go through this "How Stuff Works" site and get a better understanding on how a GPS receiver works.
GPS Tutorial from Trimble
GPS is a complex technology but understanding it can be quite easy if you take it one step at a time. This tutorial is designed to give you a good basic understanding of the principles behind GPS without loading you down with too much technical detail.