Universal AutoCorrect.

Spellcheck autocorrect everywhere on the fly in the background and you can teach it to make it better.

1. Download + install Autohotkey.
2. Download + Doubleclick the Autocorrect Script.

Notice the little H on the task tray?

Now, in any application, like even Diablo 2, you have a good degree of automatic spellchecking.

To add your own simply highlight a misspelled word in any text box and hold down the windows key and hit h.

Someone give this man and the AHK people a medal.