Tu Do (tuhdo) has an excellent series of primers on Emacs. The first one is the Emacs Mini Manual (PART 1) - THE BASICS. It's about 40 pages when printed as a PDF so it's much more than an extended cheat sheet. There are two more mini manuals covering Elisp and extending Emacs. There are also other articles on various Emacs subjects.
Part 1 of the mini manual is the best introduction to Emacs that I've seen. It covers everything you need to know to be an effective Emacs user. This includes topics like Dired, Macros, Registers, Ido, Version Control, and Shells as well as well as the usual navigation, search, and dealing with windows and frames subjects.
The mini manual reminds me of the Org Mode compact guide. It's a shorter version of the complete Emacs manual optimized for getting up to speed as quickly as possible without drowning in all the details that the complete manual provides.
Even if you're an experienced Emacs user, there's probably a few details that will be new to you so it's worth taking a look at it. I learned a couple of features about Dired that I didn't know so it was very worthwhile for me.
At the end of the tutorial, tuhdo quotes a post, The Ghost in the Machine, by José Antonio Ortega Ruiz that captures my feelings about Emacs perfectly. He says that Emacs fills our yearning for a Lisp Machine. I've often written similar sentiments so I can relate. Those of us who try to do as much as possible in Emacs tend to think of it as a light weight Lisp Machine.
I haven't read the rest of the manuals yet but I intend to. If they're as good as Part 1, I'm sure to learn some new and useful things. If you've already read them, feel free to leave a comment.