When Toyota launched a social network for drivers of hybrid vehicles, I lamented that too many social networks would result in people dividing their time between several and getting fully involved in none. Seriously, how much time can you spend in social networks when you belong to one for the car you drive; one each for the baseball, basketball, football and hockey teams you follow; one for the kind of work you do; one for your hobby; one for a cause you believe in…

I much prefer the idea of a MySpace-like environment in which you belong to a single network and then break out into groups of common interest. It just makes more sense to me. Marc Andreesen, though, is taking social networks in the opposite direction. The leader of the team that launched Mosaic, the first web browser, some 14 years ago (good grief, has it been that long?) is one of the minds behind Ning, a website that lets anybody start a social network on any topic they want. Some of the early entries include networks on microbrews, “American Idol,” crime fiction writing…

I can’t tell how many have been created so far, but it appears there are nearly 2,000 pages of listings, with 20 listings on a page, which would account for 40,000 networks. Like other social networks, these each include members (a listing of people who have joined the network, the equivalent of MySpace “friends”), a discussion thread, a blog, videos and photos uploaded by members and a discussion forum.

It’s easy enough to invite friends and colleagues to one of these networks, and some—like one dedicated to the TV series “Battlestar Gallactica”—amass big numbers. Others are closed, like one for the faculty of a high school, which actually makes pretty good sense. Private networks for people who already have a connection through work, church, school or some other activity can be incredibly useful.

Highly specialized networks also will attract high levels of participation, like the one Reuter’s is launching aimed at fund managers, analysts, and traders.

In general, though, I’m skeptical that a bajillion social networks will make for good social networking. It’s not that people won’t join networks like “The Classical Guitar Network” (although it does have only one member so far); it’s that people will belong to so many that their participation will be cursory rather than fully engaged. Nope; sorry. I just don’t see it.