Inspired by the similar functionality in XPerl Unit frames, this addon allows you to see who is missing a given buff or debuff in your raid by hovering the mouse over a buff (or who does have it by holding down alt).
Default modifiers
No modifier: Shows who does not have the (de)buff
Holding down alt: Shows who does have the (de)buff
Holindg down control: Shows who cast the (de)buff if known (the caster needs to be within range to report this)
Slash commands /bw or /buffwhoon show current modifiers and allow you to change default behaviours in the interface options screen.
Doesn't require Xperl or any other unit frame addon.