Some plug-ins I always keep in my .vim/ directory:

• vimspell: Very useful for writing important e-mails.

• Switch buffers (with Ctrl-Tab)

map <C-TAB> :bn<CR>
map <C-S-TAB> :bp<CR>

• Marks
• regexp replace (:%s/xxx/yyy/c)
• vimdiff ( [c ]c do dp)
• search next/previous char (f/F repeat with ;/.)
  • f includes the character (use with 'c' with the last letter to change)
  • t doesn't include the char (use with 'c' with the following letter)
• use registers
  • “1 is previous yank, etc…
  • “ay yanks in 'a' register
• indentation
  • == for current line
  • = in visual mode
  • =a{ current {} block
• visual mode
  • aB select a {} block
  • gv selects previous block
  • v exchange start/end in visual mode
• command line editing (searching files to edit…)
• print a control character verbatim (e.g. ^M) by using ^V
• Tags
  • C-] to jump to def, C-t to come back
  • g] to show a menu before jumping
  • C-W } show the tag under cursor in the preview window, C-W z to close qf
• Command line editing:
  • C-D show all possible completions
  • C-W delete the last word
• Macros:
  • q{a-z0-9} to record in said register (uppercase to add)
  • q to stop
  • @{a-z0-9} to execute the register (@@to repeat the previous)
  • to run a macro on every line of the selection: :'<,'>normal @q
  • on every line of the file: :%normal @q
• Increment/decrement the number under the cursor: C-a/C-x
• Spelling:
  • Suggest a correction for the word under the cursor: z=