True, it may be a rat snake, but... do rat snakes rattle the end of their tails like a rattler would? That's what really threw me (after I thought about it). I mean... do ALL snakes do that when aggrivated? O.o?

Many snakes 'rattle' their tail as a threat. Just look thorugh pictures of your native snakes until you find a matching one. Long and skinny and dark = black racer?

if you have the pic in photobucket or Picasa, they give you the code to use (pick the HTML code). http://edis.ifas.ufl.edu/uw251 identifies all the common "black snakes" in Florida. Several of them have light chins, and none of those are poisonous.

No worries. It is either a Black Rat Snake or a Northern Black Racer. Both species are nonvenomous and harmless.