[nabs]

my thought is "warped" rotors... its a common problem amongst honda/acura's i hear.

the rotor is technically not warped however the brake pads become uneven on how they sit on the rotor causing the noise/vibration.

I have the same issue with mine where I hear the problem rather than feeling it, i believe its the suspension of the car helping me not feel it. A fix would be to get the rotors resurfaced and get higher quality brake pads ive been told. The reason you must resurface the rotor is that sediments of the brake pad would be left on the rotor and over time they get rock hard which causes the "rumbling".

unless you have drum brakes, then i don't know.

edit: I agree with G-spec... I am getting new rotors and pads because I have been told the problem will come back if i do not change the rotors.