An item I found running maraudon for no particular reason was the
[Razorlash Root], again on the HS cooldown, but I guess is something on that cooldown for mana.
Also another cute one is the
[Bogling Root], something like 3 boglings spawn while doing some very early quest in the NE area, dropping one root each.
I also remeber hearing reports that
[Bag of Marbles] was a rather powerful item for some fights, think the context was reguarding maexxna during the stuns as an easy way to help the tank survive. Don't know if these still work on everything, but at the time there was nothing that resisted them at all.
Almost out... also some magic dust from the elementals in westfall,
[Magic Dust] never tried it in PvP or anything, but I suspect that may work nicely depending on its resist mechanics (caster vs item level being used).