A friend in Silicon Valley tells a story about Facebook. He's a guy about my age (late 40s), and like almost everyone else in the Valley he recently joined this social networking Web site that was originally for college kids but now has become the hip place for business folks to connect. My pal, who teaches at UC, Berkeley in his spare time and is a well-read guy, joined a Facebook club called "Reading Is Sexy" and checked out a chat thread titled, "fav author normal people have never heard of." Among the writers who garnered high praise were such super-obscure names as Margaret Atwood, Jorge Luis Borges, F. Scott Fitzgerald, Gabriel García Márquez, Edith Wharton and Eugene O'Neill. Of the last it was said, "He's an American dramatist and he's amazing!"

Who knew? O'Neill, is it? I'll have to check him out. Especially 'cause he's amazing! Probably awesome!, too.

Slideshow: The Stranger Side Of Facebook

Slideshow: Popular Social Networking Sites

Slideshow: How To Network Like A Pro Online

Slideshow: Web Sites You Must Browse Through

Slideshow: Unmasked On The Web

I'm sorry. It's easy to make fun of Facebook. But I don't get all the excitement. At least for anyone over the age of, say, 25. Here's how it works: You create a profile that includes your date of birth, home town, high school, college, employer, political views, marital status and so forth. Then you start inviting people to be your friend. Other people invite you to be their friend, too, including people you don't even know.

You can publish photo albums, join groups and send e-mail messages. You can leave notes on other people's "walls" or give them a "poke," which is the online equivalent of saying, "Hey, I've got nothing to say." On the sillier side, you can send someone a virtual martini or give them a virtual "bite" that turns them into a virtual "zombie," at which point they can virtually zombie-bite you back. In May Facebook opened its site up to outside software developers, and now there are 3,000 applications that let you hatch a dragon and raise it online, take an IQ test, show off which cities you've been to or find out which celebrities you resemble, personality-wise.

Facebook was created in 2004 for college students but in 2006 threw open its doors to nonstudents as a gambit to boost its traffic. It worked. Facebook adds 200,000 new members every day, and the site is one of the most popular destinations on the Web, with 54 billion page views per month.

I'm a member in good standing and a daily user of the site, but I'm beginning to grow concerned about time spent there. At the risk of sounding both dyspeptic and cynical, to me the main problem with all these Facebook applications is that they don't solve any real problems in my life and only serve as a vehicle for showing me more ads.

Same goes for Facebook in general. I just can't shake the feeling that I'm being lured into some carnival tent and encouraged to perform stupid tricks--fill out quizzes, send zombie bites--just so hawkers can grab me and try to sell me stuff and so Facebook's founders can all get obscenely rich.

That they might. Facebook's ad revenue runs about $150 million a year, but some folks (including Facebook management) reportedly believe the 300-employee company is worth $10 billion or more. It says something about the crazy bubble mentality gripping Silicon Valley that even this last reason does not turn people off. Rather, it seems to make people even more eager to use Facebook. Roger McNamee, a Silicon Valley venture capitalist whose hair is most definitely graying and whose firm, Elevation Partners, owns a stake in Forbes, has a personal investment in Facebook. He's also an active poster on his friends' walls.

Oldsters are swarming onto Facebook, tilting the demographics so that today more than half of its 43 million members are not college students. We're also changing the way Facebook gets used, from a place where college kids keep track of one another and meet new friends and "hook up," to a place where businesspeople do a lot of networking. They send silly virtual gifts to break the ice with sales prospects. You can announce an upcoming business trip to your Facebook network and see if any colleagues will meet you at an out-of-town bar or restaurant. Employees from Citigroup, ge, Procter & Gamble and Shell Oil have formed Facebook groups. I'm using Facebook to promote my blog and novel. One blog reader voluntarily created a club called the "Fake Steve Jobs Appreciation Society," which now has 249 members. Thanks to Facebook I can tell these folks about bookstore appearances that I'll be making.

But the weird side of Facebook is that, while loads of oldsters are jumping on board, the site still looks and feels like a place for kids. There's a big emphasis on figuring out what kind of person you are and how many friends you have and which ones are your best friends forever. You can spend a lot of time rating your favorite movies, TV shows, books and music.

I tried the very popular Flixster movie application after a forbes colleague sent it to me, but halfway through the quiz it occurred to me the whole thing was pointless. This colleague is my friend, but who cares whether we like the same movies? Same goes for the iLike music application. It's fine. It's fun. But do I really want to want to sit here making a list of all the bands or albums I like? I'm married, with two kids; I'm not trying to find a soul mate who shares my taste in music.

It's as if two very different tribes were trying to inhabit the same space. I sometimes get the creepy feeling that we oldsters are barging into some college party where we don't belong and trying a little too hard to look like we're having fun, like the sad middle-age guys in the movie Old School who attempt, pathetically, to recapture their college days.

A lot of otherwise sensible adults tell me they find Facebook weirdly addictive. As one told me, "Instead of Facebook, they should call it Timesuck." Facebook is especially all the rage in the world of tech, particularly in the p.r. and marketing end of the business. So is Twitter, another so-called social media site that lets people blast a constant stream of 140-character status reports to anyone who wants to receive them.

Example:

I'm walking into the Starbucks on 3rd St.

I'm ordering a mocha latte.

I'm paying for a mocha latte.

I'm drinking a mocha latte.

You get the idea. At first glance this might all seem like ceaseless nitwittery, millions of meaningless megabytes zipping through fiber-optic lines and swarming in the air around us, for no good reason, simply because we can. Unfortunately, it kind of looks like that on second glance, too.

Over time this could change as the thousands of applications being written for Facebook include more that make the site useful for grown-ups. Some are already starting to make a bit of money. But many applications are only virtual variations of high-fiving people.

Once upon a time the darlings of Silicon Valley were companies making things like chips and software, computers and networking routers. Hot shops were Cisco Systems, Oracle and Sun Microsystems. Then came Netscape. Then Google. Right now it's Facebook, a sort of corporate version of Paris Hilton--a company that's famous for being famous. Soon it will probably also be rich, though right now nobody quite knows why.