split your team up.

take them to an instance or two to get some gear. i know... its not dual boxing, but it helps. heck, at 67 just go do some of the really fun group quests that give you good gear. there's a bunch in nagrand (durn, ringoblood, some jumping quest for eggs). if you run instances in duo, make some macros just for instances in order to heal tanks and other party members while still dpsing on your shaman. some fun to be had.

and get your team the undead slaying gear. its not too hard at 67. just make sure you have a tank, and your priest can heal the tank while the shaman dps. its very easy to take down these nexus crystals with even a 3 man group if you know what you're doing. with a warrior/priest and holy nova, you can pull the entire camp. dps? what dps?