The bar which pops up that "X new answers were posted. Load?" while typing an answer is nice, but so many people just ignore it. Which sometimes ends up in a flood of identical answers, especially when the question is trivial.
I propose that loading the answers is obligatory - the answer being typed can't be saved before the user clicks the "load" button and the answers are shown.
Hopefully, when the user sees that similar answer was already posted, he won't bother submitting the answer.
Some PHPBB forums go even further aspect - they check if there are unread posts while saving the answer (and require further confirmation before saving the answer).