In my recent foray into podcasting, I ran across a gem. It is a 4-part series which explains most of the basics of networking in easy-to-understand terms. The series is part of what is called Security Now from the guys who do This Week In Tech. It covers the basics of IP, the difference between TCP and UDP, ethernet, DHCP, subnet masks, etc. Everything you ever wanted to know about networking. If you haven't had a chance to read a book or take a class on networking, this is a great introduction to the world of networking that is enveloping all of us. The whole series takes about 3 1/2 hours.
The episodes of note are:
How the Internet Works, Pt. 1
How the Internet Works, Pt. 2
How LANs Work, Pt. 1
(If you haven't tried podcasting yet, give it a shot. It makes for an informative commute.)