I would love to see 3rd party support for popular charities. They all have donation pages setup already so all it would take is setting up a link that works with overlays or lightstream directly. Also would be possible to give subs and option to add a $1 or something to donate monthly to the streamers select charity.
Lastly maybe something in skills could be implemented to directly effect mixer users as well. Maybe a charity section to donate sparks and they could be cashed out at certain tiers to auto donate or something. This would be really useful for charity streamers like myself.