maybe this is doable with an addon or some combo, i dunno...
i'm in a few arena teams. it would be nice if when i cast sheep, my team mates would get an indicator of a pending sheep on my target -- perhaps a countdown to when the sheep will be finished casting. then, a bar would stay up on their screen with the sheep expiration ticking down.
now i'm not thinking this would only be for sheep, but for blind or cyclone or whatever else. maybe even dots.
wouldn't need to be specifically arena teams, but that's the most regular, controlled circumstance and what made me think about it.
i was thinking of a layout where you had your potential enemies listed next to each other and any effects could be listed under/over their name. maybe even compressing cc's or dots into single, longest duration bars rather than a big mess of things once stuff gets going.
presumably, you'd need to broadcast your spell casts/interrupts/misses/successes and also pass on some info about that spell (target, time left in cast, expected duration of spell, etc).
probably should be targeted towards arenas cuz i can't imagine how this would work in something like av -- way too much data bouncing around, altho maybe could filter it based on enemy proximity or something...