After a recent occurance this suggestion arises from me.
After writing a fair amount of text I managed to clip the back button on my mouse and thus lose everything written.
It would be quite convienient to have an 'Are you sure you wish to leave the page?' confirmation when you have text in either a forum response or PM. As this would stop the accidentle deletion of such post's content.
Not sure on the complexity of implementation as my web dev skills are pathetic :(