Can someone be a carrier of the hiv virus, pass it on to others but never develop the disease himself/herself?

No: Although, passing of the HIV virus from asymptomatic carrier is a well documented fact, i refute the possibility of the carrier not getting aids himself w/out treatment, as the virus slowly (sometimes, actually pretty fast) destroys the host's immune system causing aids (end stage of the HIV disease).

Yes: A rare individual is not affected by HIV and thus you should always be on the alert and take the proper precautions.