I know, I know, this can be very expensive, but PPC can be the quickest way to get quality traffic to your sites. Just be careful and approach it with kid's gloves until you find campaigns which work for you - then scale them up. Microsoft Adcenter and Yahoo Marketing have now joined forces and I find this is producing good traffic for me. Google Adwords is probably better, but they are a real pain to work with and have become too expensive, at least for my keywords. But if you have the resources, don't rule out Adwords or any of the PPC programs.