After having been buzzed by more boats than I can recall, and having heard about many injuries (and fatalities) that resulted from diver-boat interactions, I am happy to see that more information is being presented to help prevent this.
I fly the 'Diver Down' flag:
As well as the Alpha flag:
when I dive off my boat. I still get many vessels (granted they're mostly powerboats or PWC's) driving right over me when I'm submerged.
Here is a PSA produced by DAN (Divers Alert Network) (I hope it get's widely distributed):
(click on link): Dive Flag Awareness Public Service Announcement