Investing in blogs

Yes there might be an opportunity.

But many of the popular blogs are owned or managed by a privately held company that are currently being funded by angel and vc funding (see federated media as an example).  Or they are a subsiderary of a traditional media company. 

So right now here are the investment options: it's research and wait for the IPO for the privately held; or through your millions into a vc offer; or buy traditional media shares.

Best of luck 

Although some blogs may be open to private financing, those pounding the pavement for money typically go the vc route, or do friends & family.  By large the funding of these successful blogs is actually from ad revenue, which fuels their own growth.  The overhead on most blogs is purely time and intellectual capital, which means very high margins and less of a need for investment dollars (they simply decide to maintain their ownership position).