Rocky Road makes a good looking and reasonably priced rack system. I believe Thule or Yakima crossbars could also be used with their roof rails, if one desired wider crossbars for any reason.
Part of the problem with the factory rack system, in my opinion, is that there is not enough space between crossbars for those of us who wish to carry larger (18'6") canoes or sea kayaks, or even the larger fiberglass boxes. At the very minimum, I would like to see at least the capability of a 48" spread between bars, rather than the factory's skimpy max of 28" or so. I believe this could be accomplished using the factory rail system, but so far i have seen nothing that approaches this spread distance. If anyone discovers such a system, please post the info for the rest of us. Thanks.
Ha! Just discovered Moose's thread on installing the custom 54" rails created by Rack Attack that provide a crossbar spread of 48" or more. This definitely looks like the only solution (although expensive) for those of us looking for a bigger bar spread. Thanks, Moose!