The Second Life Knowledge Base can be found here:
An interactive tutorial for newbies and created by Lindens can be found here:
Orientation Island Public http://slurl.com/secondlife/Orientation%20Island%20Public/100/170/33
There is a good overall collection of notecards for newbies here:
AnnDe's Designs http://slurl.com/secondlife/Rhee/121/156/128
Credit to PI en Second Life for these two links to a collection of video tutorials, beginner to advanced:
From the Mermaid Diaries: