How do we solve the vexing problem of online advertiser and audience fragmentation? Why, the network, of course. Aside from a few big names, very few sites today have the quality and reach that advertisers want. (In many cases they would just settle for low volume, high quality.) This is another angle on the "inventory problem" discussion.
A case in point: I had a conversation with Gabriel Gross, CEO of RealBird, which provides maps and data to third-party real estate sites. He would like to provide advertisers access to his maps, but there's lots of pain in trying to reach the advertisers that might really want to be there. And there are plenty of advertisers that would indeed want to access the 2.5 million monthly, highly (geo)targeted consumers his mapping tools reach.
What's the solution? A network that would allow advertisers access to inventory on or around his maps. But that network doesn't yet exist. Creating networks that bring together the millions of sites out there that might not themselves have lots of traffic but in the aggregate could offer both reach and quality is one answer to the inventory problem.
But who will build that network and when?