There is a great thread on reddit about what emacs commands you find most useful. Some real gems in there:
jimm 4 points 11 hours ago[-]
Instead of using C-u 9999 C-x e, try C-u 0 C-x e. From the docs: "With numeric prefix arg, repeat macro that many times. Zero argument means repeat until there is an error."
flazz 8 points 18 hours ago[-]
we need an emacs mode to generate a histogram of most used commands and keystrokes!
rgiar 8 points 8 hours ago[-]
google for keyolution.el
petteri 1 point 8 hours ago[-]
M-x comment-or-uncomment-region . I have key binding for this (define-key global-map "\C-z\C-c" 'comment-or-uncomment-region)
MentalSiege 5 points 18 hours ago[-]
mark-whole-buffer is useful. It's on C-x h.