I don't really care about a true wysiwyg editor, just buttons/drop-downs to insert the bb-code tags into the message. The ones I don't use a lot (font, size, color, alignment, for example) I always have to look up (the link to the reference page is also gone, BTW), and even lists would be a lot easier with buttons. Just have a look at the Adventure Gamers forums to see what I'm talking about.
Oh, that reminds me: they also support keyboard shortcuts, so that you can select a piece of your text and just press Ctrl-B or Ctrl-I to bold or italicize it. That would be also be very nice to have.