One of the more interesting non-polemical bits from Fagan's The Long Summer was the idea of ecotone-straddling. This is a practice of groups which settle on the borders between one habitat ("ecotone" is the term he used) and another. That is, instead of planting your village in the middle of a plain, or in the middle of the hills, you want to settle on the edge of the plains and the hills. When the weather and season favors the grains and animals of the plain, you can live off of the bountiful plain. When the weather or season turns the other way, you can go hunting, or harvesting nuts and such, in the hills. The idea is a sort of hedging of bets - by placing yourself on the edge of two or more habitats, you can enjoy the safety of an ecological back-up.
You can sort of see the same effect occurring in the blogspheres. People whose reading and links are largely within the same ideological habitat, are less fruitful of interesting material than those that straddle real ideological divides. Someone with one foot in libertarian circles, and another in leftist circles is going to have more to talk about to each side of the divide, largely because she's going to be able to pass material gathered in one circle, and offer it as a novelty in the other circle. But it also means that actual news that won't grab the denizens of one circle, will be interesting to the other. Thus is avoided the dreaded blog-famines driven by temporary droughts of originality, ambition, or interest.