With Twitter’s API application, there is potential for many new applications to be built off the Twitter back-end (although, not quite yet Twitter usernames are essentially keywords used for these applications built on the Twitter platform — and Twitter username squatting is happening. The question is, how will these new businesses monetize — and how will Twitter itself monetize: The power in any advertising-supported website, publication, TV show, etc, is community (readers, viewers, listeners, etc). Build a great service, get people to use it (or read, listen, view) and you can then send out specific ads to those users. Example 1: Have a Twitter username for "Knicks"(i.e. NY Knicks, a basketball team in the NBA). People add that user as their friend — the "Knicks" username pushes out any Knicks news… the minute it happens! Ditto on sports scores — if a Knicks game is going on, it’ll send out the score during the game to keep you alerted, if you want to be. If you can get 10,000 Knicks fans on your list — then you can either:

1)Put an ad in any blank space at the end of your 140-character messages — i.e. "Drink an ice cold, refreshing Pepsi."

2. Send out an advertisement every 10th or 50th (whatever you learn to be OK with your users) twitter. Thus, I may receive 10 twitters of news announcements, and the 11th is an advertisement for Grey Goose vodka.

3. Pay-Per-Twitter Message — If there was a username called "NYCtechJobs" — any person looking for a tech job in NYC could be a friend of this list, and be notified instantly of any new NYC tech jobs. Where would those jobs come from? Initially possibly just from Craigs List, Monster, Hot Jobs, etc … but then say you have 2,000 users that are the friends of "NYCtechJobs", that means you have 2,000 prospective tech employees in the NYC area. A company would love to get their latest tech job out to those prospects, so they can find a hire — thus, they go to a web page you have setup, and they are able to create a message up to 140 characters (likely include a URL to full job details) with some details on the job. You can charge the employer for posting this.

Ditto with a list (er, username) like "NYCfurniture". People could pay to broadcast their message to all of the friends of "NYCfurniture".

4. Charge for access to your Twitter messages — Your username can be private and only your friends can receive/view your twitters. Thus, if you had valuable/timely information — you could have a subscription-based service where you charge $X for people to be your friend, and then they would have access to your twitters. Thus, a celebrity could charge for this — or a newspaper might do this to give you access to the news first — or some blogger that finds online shopping deals could send them to you … basically, if the user wanted to be "in the know" for whatever offering, they’d pay $X for access (per week or month). Note: You’d have to verify their subscriptions — and if they haven’t paid for the month, you’d remove them as a friend from your Twitter account.

5. Commissions on user purchases — Setup a service that allows users to buy products through this. User would need to setup an account with you with their credit card (or PayPal info, or a deposit into this proposed payment service) stored. I imagine a user could be browsing Wired magazine and be able to quickly purchase a subscription for $10 by ripping out their cell phone, Twittering a code like "d buy wired", with a confirmation coming back to the user and them approving the confirmation possibly using a password, then the transaction occurring.

The biggest question on everyone’s minds is what Evans Williams is thinking. They’re opening up their back-end to allow the development of applications on the Twitter platform (which I think is real smart, because people are going to build useful applications for Twitter users — and everyone will be using Twitter in some capacity more often) … but will Evan plan to charge these companies that are building apps? Will Evan not want these apps monetizing themselves? How is Evan planning to monetize Twitter — or will he sell and leave that to a Yahoo/Microsoft/News Corp to figure out how to extract value out of the massive userbase (like his sale of Blogger to Google)? I don’t think Evan knows the answers quite yet — he’s just focused on building a great application for users.