Advanced Emacs Commands

Common default Emacs key prefixes
Key prefix      Description
C-c             Commands particular to the current editing mode
C-x             Commands for files and buffers
C-h             Help commands
M-x             Literal function name
C-h b           Show key bindings

Emacs window-manipulation commands
Key               Function                   Description
C-x 4 f           find-file-other-window     Open a new file in a new buffer, drawing it in a new vertical
                                             window.

undefined         scroll-all-mode            Toggle the scroll-all minor mode. When it's on, all windows
                                             displaying the buffer in the current window are scrolled 
                                             simultaneously and in equal, relative amounts.

C-x 3    split-window-horizontally           Split the current window in half down the middle, stacking the new
                                             buffers horizontally.

undefined         follow-mode                Toggle follow, a minor mode. When it's on in a buffer, all windows
                                             displaying the buffer are connected into a large virtual window.

C-x ^             enlarge-window             Make the current window taller by a line; preceded by a negative,
                                             this makes the current window shorter by a line.

C-x }   shrink-window-horizontally           Make the current active window thinner by a single column.

C-x {   enlarge-window-horizontally          Make the current active window wider by a single column.

C-x -   shrink-window-if-larger-than-buffer  Reduce the current active window to the smallest possible size for
                                             the buffer it contains.

C-x +            balance-windows             Balance the size of all windows, making them approximately equal.

undefined        compare-windows             Compare the current window with the next window, beginning with
                                             point in both windows and moving point in both buffers to the
                                             first character that differs until reaching the end of the buffer.

Emacs text manipulation commands
Key              Function                    Description
C-x Tab          indent-rigidly              This command indents lines in the region (or at point).

undefined        fill-region                 This command fills all paragraphs in the region.

M-q              fill-paragraph              This command fills the single paragraph at point.

M-\              delete-horizontal-space     This command removes any horizontal space to the right and left of
                                             point.

C-o              open-line                   This command opens a new line of vertical space below point,
                                             without moving point.

C-t              transpose-chars             This command transposes the single characters to the right and
                                             left of point.

M-t              transpose-words             This command transposes the single words to the right and left of 
                                             point.

C-x C-t          transpose-lines             This command transposes the line at point with the line before it.

M-^              delete-indentation          This command joins the line at point with the previous line.
Preface with C-1 to join the line at point with the next line (C-1 M-^)

M-u              uppercase-word              This command converts the text at point to the end of the word to
                                             uppercase letters.

M-l              downcase-word               This command converts the text at point to the end of the word to 
                                             lowercase letters.

C-x C-l          downcase-region             This command converts the region to lowercase letters.

C-x C-u          upcase-region               This command converts the region to uppercase letters.

M-m              back-to-indentation         This command, given anywhere on a line, positions point at the 
                                             first non blank character on the line. 

C-s C-w                                      This command, add the (rest of the) word at the pointer for search

Emacs commands for using registers
Emacs registers are general-purpose storage mechanisms that can store one of many things, including text,
a rectangle, a position in a buffer, or some other value or setting. Every register has a label, which is
a single character that you use to reference it.

A register can be redefined, but it can contain only one thing at a time. Once you exit Emacs, all registers
are cleared.

Key               Function                   Description
C-x r space X     point-to-register          Save point to register named X.

C-x r s X         copy-to-register           Save the region to register named X.

C-x r r X         copy-rectangle-to-register Save the selected rectangle to register named X.

undefined         view-register              View the contents of a given register.

C-x r j X         jump-to-register           Move point to the location given in register named X.

C-x r i X         insert-register            Insert the contents of register named X at point.

Emacs commands for using bookmarks
Emacs has another facility for saving positions in buffers. These Emacs bookmarks work the same as registers,
but their labels can be longer than a single character, and they're more permanent: If you save them, you 
can use them between sessions. They persist until you remove them. As their name implies, bookmarks are 
handy for saving your position in a buffer so that you can return to it at a later time, most often during a 
later Emacs session.

Key               Function                   Description
C-x r m Bookmark  bookmark-set               Set a bookmark named Bookmark.

C-x r l           bookmarks-bmenu-list       List all saved bookmarks.

undefined         bookmark-delete            Delete a bookmark.

C-x r b Bookmark  bookmark-jump              Jump to the location set in the bookmark named Bookmark.

undefined         bookmark-save              Save all bookmarks to the bookmark file, ~/.emacs.bmk.
                                             (you can redefine it)

Emacs commands for using rectangles
Did you ever wish you could select a box of text from a document for copying, killing, or yanking purposes?
You can. In Emacs, a selection of text specified by any two opposite of its four corners is called a rectangle.

Key               Function                   Description
C-space           set-mark-command           Marks one corner of a rectangle (point marks the opposite corner).

C-x r k           kill-rectangle             Kills the current rectangle and saves it in a special rectangle 
                                             buffer.

C-x r d           delete-rectangle           Deletes the current rectangle and doesn't save it for yanking.

C-x r c           clear-rectangle            Clears the current rectangle, replacing the entire 
                                             area with whitespace.

C-x r o           open-rectangle             Opens the current rectangle, filling the entire area with 
                                             whitespace  and moving all text from the rectangle to the right.

C-x r M-w                                    Copy text without deleting the text from the buffer.

C-x r y           yank-rectangle             Yanks the contents of the last-killed rectangle at point, moving 
                                             all existing text to the right.

Mark rings
You should never have to scroll around randomly in a buffer to find "that place you were just looking at". 
Whenever you take a diversion (e.g. by searching, or pressing M-<  or M->), Emacs uses the mark to save 
your previous position, kind of like sticking your finger behind one page of a book while you go to glance at 
another page. You can return to the mark with C-x C-x.

However, Emacs saves up to 16 previous values of the mark, and you can jump to previous ones with C-u C-SPC. 
This makes mark and the mark ring a valuable navigation tool. You can use it somewhat mindlessly:
if you ever find yourself asking "where was I just now?" you can often just press C-u C-SPC until you
find yourself back in the right place.
  
Programming
Key                 Function                   Description
M-x                 check-parens               Checking for unmatched parentheses
C-x w h REGEXP FACE                            Highlight matches of pattern REGEXP in current buffer with FACE.

C-x w p PHRASE FACE                            Highlight matches of phrase PHRASE in current buffer with FACE.
                                               (PHRASE can be any REGEXP, but spaces will be replaced by matches
                                               to whitespace and initial lower-case letters will become case 
                                               insensitive.)

C-x w l REGEXP FACE                            Highlight lines containing matches of REGEXP in current buffer 
                                               with FACE.

C-x w r REGEX                                  Remove highlighting on matches of REGEXP in current buffer


Tips:
C-SPC                                          Make mark in some place and then disable it with C-g
                                               Go somewhere else and do it again and again etc.
C-u C-SPC                                      Back to previous mark, and back and back etc.
M-x re-builder                                 Helps you to create needed regular expression.

Highlighting Regexps, Phrases, And Lines
Key        Function                          Description
M-s h p    highlight-phrase                  It will ask you for a phrase and highlighting color and then highlight
                                             all the matching phrases in the buffer.
M-s h r    highlight-regexp                  Highlight anything that matches an arbitrary regexp
M-s h l    highlight-lines-matching-regexp   Highlights the entire line that contains the match to the regular expression
M-s h u    unhighlight-regexp                Un-highlight the matches


Useful references:
Emacs Tutorial
Beyond Emacs Tutorial
Reference Card