Blasted lands
Great quest to do at around 54 is The Stones That Bind Us. After you complete it (7550 xp) , you walk 10' and turn in to another npc(3000 xp) then click on the chest that appears and receive 6000 xp and
http://wow.allakhazam.com/item.html?witem=10659 16,550 xp! You can find the starting npc(his name is Fallen Hero of the Horde) at the entrance to Swamp of Sorrows when coming from blasted lands. He's just off the road on the right.
Lots of good quests in Felwood and later in winterspring