What does increased magic find do?
What does 100% magic find actually do? I've been above it but I still find non-magical items.
It doubles your base chance of finding magical items. So if the base chance of a specific drop is 5% and you increase it by 100% it is now 10%. But it doesn't mean that when you have 100% magic find you find magic items all the time.
The base chance of the drop (likeliness of appearance of a magical item) is tied to the level of the monster you kill or the difficulty level and area of the container you open.
Note that the modifier full name is:
If you equip your follower with magic find only 20% (one fifth) of that magic find adds to your magic find.
If you are playing with other people, each of you gets the arithmetic average magic find of the whole party. And (unlike previous Diablo titles) each of you gets and sees his own drops only.
Also see here.