Useful spell check commands:

• z + =: Spell check. Type number choice followed by enter.
• ] + s: Go to next misspelled word
• [ + s: Go to previous misspelled word
• z + g: Add word to good word list
• z + w: Add word to bad word list
• z + u + g: Undo adding word to good word list
• z + u + w: Undo adding word to bad word list

To activate spell check, add the following to your .vimrc file (en is for English):

set spelllang=en
set spell