The "big excitement" over social networking sites is beginning to smell like the portal boom of the 1990s.

And to think it all started with Kevin Bacon. The picture to the left was taken from a CNN story on the eponymous game, the idea being that everyone is within six links of the heavily-networked Hollywood actor. (Bacon himself once did an American Express ad on the theme.) (UPDATE: John A. Stoner points out that was a Visa Check commercial that Bacon did. As a prize you get to move one degree closer to him, and to me.)

Social networking sites try to get everyone together to make friends or do business based on the concept of getting invited by someone you know, the idea being that you'll then invite your friends and participate, growing out your network until, like Bacon, you're connected to everyone.

Bacon's a good actor, but this concept has always smelled to me like smoked, salted pig belly. At minimum, we can say it's not to everyone's tastes.

So why all the big money? Everyone wants to win the "personal networking space," just like everyone wanted to win the "portal" race "back in the day." I'm afraid the result will be the same here as it was then, a lot of hurt.

There are all sorts of networking sites, and I belong to two -- Ryze and linkedin. I have spent no money with either site, and gotten no work as a result of my participation.

That should tell you all you need to know. The play should be to wait and see if one of these things can make money, then buy it for a decent multiple. But that is not what is happening.

Despite the fact that these things are really easy to create (Clay Johnson and friends built DeanSpace in a matter of weeks), we see big companies headed by smart people wasting big bucks trying to recreate the wheel.

Among the most Clueless operations is Google's Orkut. The thing has already become a parody -- I found this on Joi Ito's Web site. Then we have self-proclaimed genius Barry Diller buying ZeroDegrees.

The Reuters story on this, which I found at The New York Times, provides ample evidence of how frothy this market is simply by listing the participants -- Friendster, Tribe Networks, CraigsList, Contact Networks, Socialtext, Spoke Software, Visible Path and Eliyon -- in addition to all those already mentioned.

By now I expect I'll be deluged with tons of comments from the adoring fans of these sites. I hope so. It will mean you're all in my social network.