When I upvote/downvote a question or answer, the arrow turns orange (in the StackOverflow case) and afterwards, my vote is cast. If the vote fails to cast, for reasons like loading error or vote cap, I get notified afterwards, but the arrow stays orange.
I know it is a minor improvement, but I would really like the arrow to indicate that it was loading (maybe grey arrow with orange halo or something, maybe even a spinner) and when the vote was cast, the orange arrow could emerge.
It's a minor nuisance for me, but I love sitting random places and answering/voting/reading SO on my iPad, and I have noticed a lot of the votes I cast never register, since I leave the page before the vote-load is completed.
Any indication would be nice.