Filter Star 1.1
Filter Star is a text filter/replacement plugin based on the Civil Tongue plugin. It replaces any string of characters with a corresponding string, as specified in the settings page. So, you can use this for filtering bad words, making smiley codes, and more.
Furthermore, it doesn't change the actual post/comment body. It only replaces text when the page renders, when the preview button is pressed, etc. So when you edit your message, the good old bad words, smiley codes, etc. are still there. As of version 1.1, you have the option of filtering discussion titles, with the caveat that those changes are permanent.
Hope someone finds this useful. I believe there is a similar addon for Vanilla 1 forums, but not for Vanilla 2.
First three screen shots are of version 1.0. Next three are of version 1.1.