Bossmods timer bars, range windows for range mechanics, extra bars unless EVERYTHING is bound (all your CC, pots, situational spells that you mighto nly use on one or two fights, i wouldn't imagine you'd have all your action bars hidden as a healer or tank, maybe some do. Personal cooldowns shown, unless you're going to 'guess' when a cooldown is up.
Boss frames if there are multiple targets to check energy (Onyxia for example) If you are a RL or just need to know you'd probably have raid CDs shown when they're on or off cooldown.
The main thing would be timer bars for whichever bossmod you were using though, quite rare to find a raider not using DBM or Bigwigs, even in the higher end guilds.
If you took 'offence' to me using the term 'LED inspired' then, i dunno, dont XD