iPhone Calculator Update

Wouldn't it be nice if the iOS calculator just added a nice little "Tip" function in their existing design? What about showing your history of calculations for us folks that have trouble remembering the factors that got us to that total? You know what, how about a voice-activated calculation? Just food for thought, but definitely some features I think would be useful and enjoyable for a math-stressed individual like myself.

What would you add if you could?