gistfile1.txt

ctrl+b
  page up

ctrl+f
  page down

gg or 1G
  top of file

G (shift+g)
  bottom of file

0
  beginning of a line

$
  end of a line

^
  first character of line

:%s/search/replace/gc
  % = entire file
  g = global
  c = confirm, interactively confirm each replacement

C
  delete to end of line and drop into insert mode

ct[char]
  delete to given [char] and drop into insert mode

yiw
  yank in word

Columnar select and insert
  ctrl+v to enter visual block mode
  select the lines you want to edit
  I (shift+i) to enter some insert mode
  make the change you want
  esc to apply the change to all the selected lines

gg=g
  reformat entire file

I (shift+i)
  go to insert mode at the beginning of the line

:tab sb app/models/user.rb
  open a buffer in a new tab

viws"
  surround word with double quotes

ds"
  delete surrounding double quote

cs"'
  change surrounding double quote to single quote

ctrl-w r
  rotate windows to the right; common use is to swap the files shown in two viewports