I would love a Choco Breeding/Raising thing that is cross app done in the kind of way the Chao were raised in the Sonic games for the Dreamcast on their VMU's. but really, my biggest hope of a cross app feature, was the card game.

It would also be nice to be able to manage your retainers and put items up for auction, recover items, etc. I think they mentioned something like this was being contemplated, but i cant remember where i saw that.

Also a FC management app where you can set buffs, accept members, promote, demote, chat, and all that good junk all from your mobile. or even a LS chat function on your device so you can keep in touch with friends when you arent online.