What can I use to drill dowel holes down the end of a long piece of wood?
Buy a self centering dowel drilling jig. Lee Valley has them, as will virtually all wood working supply sources, Rockler, for example.



The jig clamps to the end of your board, and then you drill through a hardened drill guide into the board, using a hand drill. These dowel jigs used to be much more common in the days before biscuits, pocket screws, etc.