Originally Posted by Oneiros

I'll just re-emphasize what I said earlier... you can get from 55-60 in less than 30 minutes in Slave Pens. AND you can ride there on a mount without even aggroing a single mob if you stay on the road (at least from Shattrath). Bribe 3 or 4 of your friends into taking you to Slave Pens at 55, grinding you for 30 minutes, and then you can start questing in Outlands. For me, 50-60 is pretty much the worst part of leveling so I will take any way I can to get through it quickly.