Step 1: Go on hell difficulty (or whichever you prefer)
2: Go to Act 1, Step 7 and click "begin quest"
3: Start the quest, talk to the guy and take the ferry to the next part
4: Run through and clear all the mobs
5: Once you're at the center of the chapel there will be a boss, and after the boss there will be 3 big nukers ( you need to dodge their big swings, or if you're tanky enough you'll be fine)
6: after killing the 3 big guys, leave the game and click on change quest, select the begin quest again; rinse and repeat.
I got my monk from 57 to 58 in 32 minutes on Hell. Try it out Don't forget to post your own time here ^^