My colleague Allen Stern says no. He says he might pay to use Twitter for business, but wouldn't do it just to hear what people are having for breakfast. I think I use Twitter differently than Allen, but my answer is pretty much the same as his: In theory, I might pay for Twitter, but in reality, no.Twitter is the biggest and most popular thing without a business model since Google. Twitter today, like pre-advertising Google, is hugely popular, fast on its way to mainstream (we'll know it's mainstream when it's mentioned on a TV sitcom), with a fiercely loyal and large fan base -- and completely without a means of generating revenue. Eventually, Google found the AdWords business model, and became the titan that it is today. But Twitter has yet to make that breakthrough.

Allen proposes that Twitter should do something similar to what Google did: Sell keyword advertising. My reaction to that is almost physical revulsion. Having individual words of my tweets put up for sale would cause me to abandon Twitter a lot faster than if Twitter asked me to pay.

I have nothing against advertising. (Dude, take a look at the edges of this very page. What do you see there? Advertising pays my salary.) However, advertising has its place and I don't feel like the inside of my Twitter feed are an appropriate place for ads.

If you don't use ads to fund a service, selling the service itself is the next logical step.

Allen says: "From my perspective, if Twitter was about sharing business information and ideas, I'd be more open to payment. But there's no way I am paying to read what someone had for lunch or that they are on their way to Cancun."

This is the part where Allen's use of Twitter and mine apparently diverge. I consider Twitter to be perso-professional (to use a perfectly ghastly neologism coined by my friend Phil Gomes at Edelman Digital). It's a source of professional networking, but also personal connections. I've come to genuinely like many of the people I follow on Twitter, even ones I've never met. So I'd pay to hear what they had for breakfast or what their vacation plans are. Not a lot, but a little each month. Just to stay in touch.

On the other hand, I think if Twitter started charging, many of my Twitter connections would drop the service. So even though I'd be willing to pay in theory, in fact I'd find it wasn't worth paying for anymore. It would be like visiting a bar you used to go to in college -- nobody there you know anymore, just a place filled with strangers and melancholy reminders of time passing.

I've seen several business models offered for Twitter over the months. None of the interesting ones are advertising-based. Online advertising is troubled, launching a new business based on advertising here in the closing weeks of 2008 seems like a bad idea.

One category of possible business models is "freemium," where you have basic accounts for free, and charge for extra capacity or features. Some examples of possible freemium business models:

- You can have up to 1,000 people following you for free, after that, you have to pay.

- Or vice-versa: You can follow up to 1,000 people, but you have to pay after that.

- Charge developers for access to some APIs.

- Charge for corporate accounts (like InformationWeek's), personal use is free.

- And here's one I like a lot: Private-label Twitter. Companies can set up their own private Twitter services, and give employees, customers and business partners access. A multinational company might have an internal Twitter just for employees. A consumer company could offer Twitter to customers as part of a brand-building marketing campaign. These private-label Twitter services could optionally be private as well, so that outsiders can't read messages on the private-label service.

Also, free Twitter might become part of an overall package of services, where the vendor charges for something else. But what would that something else be? I can't really think of anything.

Note that all of these business models are predicated on Twitter remaining free for most of its customers. That's essential for Twitter's survival. Because Twitter isn't really selling software, or a service, it's selling a community of people, and if they do anything to drive away a significant portion of that community, the business will collapse.