What would be crazy awesome would be a hotbar 'feat', a ...recipe or macro if you will.
You select the icon, add a bunch of buffs to it, then drag the 'macro' to your bar somewhere.
When you click on it, it either chain casts, or all at once casts ALL the buffs in the recipe/macro on the selected player.
A rather large part of the game is spent standing around for buffs, and a caster clicking through half their bars on every player for quests that require a lot of buffs.
It wouldnt have to be an 'all at once' kind of deal, to make players still wait if they wanted buffs, but just being able to save the many clicks once you know what buffs you want with one cast/click would be super, super nice.