Use TextEdit's AutoCorrect everywhere (especially in Google Chrome)
TextEdit's autocorrect is actually OS X's autocorrect, which is used in every system text box in the OS, in every application, including 3rd-party applications.

The problem comes when apps use their own text boxes—they then have to implement NSSpellChecker themselves. Whilst the Google Chrome issue relating to this seems to suggest that nothing has changed, my limited testing seems to suggest that it has been implemented in Canary.