I thought I'd written about Tony Pelaez's video on Taking Notes in Emacs Org-Mode before but I couldn't find the post. Even if I did write about it, it's a nice introduction to one of Org mode's most useful functionalities and worth mentioning again. This is especially true since I've been seeing a lot of tweets lately from people just discovering Org mode.
Pelaez's introduction is very elementary in the sense that he mostly ignores the standard keyboard shortcuts and uses menus or 【Meta+x】 command sequences instead. When he gets to demonstrating the outlining functionality—in the guise of making a TODO list—he does use the shortcuts. If you don't use Org mode everyday, it's easy to forget these so it serves as a nice review even if you're not a n00b.
If you're just starting with Org, this video will introduce you to one of its major use cases. Be warned though: you'll soon be using Org for an ever increasing portion of your workflow.