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

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