Several changes I would like to see (let's start with the obvious ones):
1) I WANT MY FAVOR BACK! Accidental donations are bound to happen, but it would be nice if you could at least recover SOME of the favor you lose by accidentally getting an emblem
2) STACKS! Please please please please make it possible for us to choose how many objects we can donate/feed/drop, etc that is not 1, 2, 3, 5, 10, 20, or 30! When donating to Giants, if I have 4000+ sparkly (which I often do) I have to donate 30 at a time, and that is just obnoxious! Same with feeding piggies 3 at a time when you have a large stack! It would be nice to have the option available to chose how much you give (like when you buy from vendor and you can choose the amount)
3) It would be really nice to have a "Reply" button for your inbox. Or perhaps you could sift through a list of friends who have recently sent you something at the mailbox so that you don't have to try to remember who sent you what so you can respond appropriately when you do come by a mailbox after receiving mail!
I think thats it! Anything to add? Anything to take away? Any devs reading this?