Credit goes to another unnamed site that I found this from, but spreading the info around...not sure if this has been posted yet.
Diablo 3 Tutorial: FAST FARMING - Whimsyshire Tree Block - YouTube
Go in and clear Teddy bears / flowers and spot all the champion packs, rares and purples first
Get 5 Stacks of Nephalem Valor from Act 1
Go in / kill the champ packs using the exploit in the video above
Switch to MF Gear before they die for extra chance at loot.