The Thagomizers. Don't know the name of the perk, but it does this: Storm Fist kills charge your Fist of Havoc and FoH kills charge your Storm Fist. Should be nice. They look sick as -blam!-, too.
That will be OP, but I think bungie will find a way to nerf it because getting your FoH in PvP by just killing someone with your charged melee will be OP and people will complain.