Here is a list of over 130 Chess lessons and tutorials in PDF and HTML format all in one place gathered from all over the Internet.
Predator at the Chessboard - A field guide to chess tactics. Lots of Lessons on tactics with practical examples and quiz's. This is a really nice free site for anyone wanting to improve their tactics.
Chesskid.com - Offers Instruction to help Kids learn Chess (Lessons and Videos Very nice)
Chess Lab - Basics are covered
US Chess Federation Beginner Course
Chess Corner Learn Chess Guide - Bunch of Very nice lessons right up to intermediate stuff.