I use
Poisonous with my rogue to keep track of my weapon buffs. Otherwise there's no real must have for me on my rogue personally.
I do have a friend who says he can't play his rogue without the mod
HearKitty. He claims the audio sound makes him realize he's at max combo points and more quickly execute his next move in his rotation but with blizzards built in visual alert I find it makes no difference to me.