Drop Rates
Edit: To be clear:
The biggest problem in Diablo 2, was the lack of drops.
We all know that Diablo 3 will have a class drop system going on, in other words if you kill that monster you get that item, no clicking required, but lets not debate on that.
Now, we all know Diablo had a bad drop rate calulator, as in you could have 1000% MF and still not find anything.
How do you want that to be handled in Diablo 3?
Do you want Items to be rare like in Diablo 2 LOD, or more frequent, so you don't need a lot of MF to get certain items.
Or do you want the MF to just disappear?