Is there an addon that does this?
It is very useful to be able to see when an important buff/condition you want to maintain is gone. And it makes your UI cleaner! While in battle, you can cast the buff to get rid of the dirty post-it sized icon bothering you.
Seriously, with these 6-20 second rapid buffs, it would be great to play whack-a-mole with positionable/resizeable icons instead of having buff timer bars that by necessity are placed somewhere on the screen I don't look.