Also important (I know it's been brought up, but just to reiterate) would be a spoiler tag function, or some other function to hide text. Media info pastes are a wonderful resource but they quickly and dramatically expand vertical space, so having some way to hide them would be good.
A full mediainfo parser like you see on AB or other sites would be awesome too, but just any sort of hide function would be a good starter (and also useful for being able to post, you know, spoilers).