In the July cover story of Wired Rupert Murdoch talks about his publishing empire. "Everything we've ever done is about giving people choices. The Net has a billion people looking for news, sports and entertainment. Another billion are on mobile phones and another couple of billion are coming up behind those. That's a hell of a lot more people making choices."
Want to create a web publishing empire? Then your marketing efforts should be structured to provide your customers with choices. Take a look at your homepage. Do you provide an entry point for each target audience? Don't make your visitor guess where to go next.
What do you know about each of your niche audiences? If you have no idea how each niche makes buying choices, then you need to do some homework. It's much easier to sell when you know what choices your customer will make.