Silver and paranormals.
Actually, Crono, YOU'RE the one who hasn't done his homework. One of the original prescribed methods for dealing with vampires (circa England, Dark Ages to early Middle Ages) was to drive a silver nail into the vampire's skull while he lay in his coffin so that he could never leave it. How someone could expect the vampire to sit still for this treatment was never explained. There have also been other vampire banes throughout the various cultures of history which have also gone out of style; to the Italians, belladonna (nightshade) was handy for keeping vampires out of homes, for example. But you don't hear too many people talking about belladonna anymore, do you? Graveyard dust, rowan wood, urine, cold iron, the vampire's true name, the Evil Eye charms, running water, something from a dead relative, a piece of the vampire's bone (good luck)...these and more became obscure while wooden stakes, holy water and garlic prospered.
I'm shutting up now before people think I'm TOO much of a nerdy vampire fanboy. Cute Flash movie, though. ;)