Well I have a few options.
1) This takes place during Warcraft 3. We play a group that lives through those events. Or we at least use those as a back ground to our own adventure. Zombies adventure anyone?
2) A traveling merchant comes across a dying traveler whom gives her/him and egg. Telling them to keep it safe at all costs. Dying man turns out to be a red dragon and the egg is the only true born black dragon to be born in since Death Wing went insane. The red dragon believes this hatchling will be the new aspect of Earth, aka replacing its father Death Wing. Mean while they are relentlessly hunted by both the black dragon flight and blue dragon flight, whom have sworn to kill every black dragon. (This was created before I found out that Thrall became the Earth Aspect and before I knew Wrathion existed. -_-)
3) ANYTHING WITH OLD GODS. Because they seem to be the root of most evils in Azeroth. Maybe the group has to stop more crazed trolls from summoning Hakkar back to the world and find that he was only the beginning.
... I swear I had more plots but I lost the lil paper I had with all my various plot ideas.