The floating combat text mods can do this sort of thing by scrolling text about the proc if you have a trigger for it set up.
MikScrollingBattleText This one does it for sure
ScrollingCombatText This one requires you to use a text file for custom events
Parrot I think this one can, not sure
If you want some kind of visual effect on procs (or any buff for that matter) then I'd suggest
Power Auras