Oprah's doing it. Conan's mocking it. And, as political shockwaves reverberate through Iran, people are relying on it.

Twitter has quickly established itself as a true Internet phenomenon.  And the San Francisco company's meteoric rise -- attracting more than 17 million unique visitors during the month of April alone -- has sparked a new wave of entrepreneurial activity from developers and venture capitalists who think they might just be able to tap into the Twitter ecosystem.

"People are antsy that you have to get in now or you will miss the boat," said Peter Denton, a developer of the Twitter business directory Twibs.

Denton's not alone. Earlier this month, former Microsoft search veteran Ken Moss unveiled a new search application called CrowdEye that's designed to help people more easily find what they're looking for on Twitter. Three days after CrowdEye's launch, VentureBeat looked at 10 other startup companies that are trying to improve the search functionality on Twitter.

Obviously, there's a lot of brain power being spent on solving that one problem alone.

It won't be easy for any of these entrepreneurial ventures to cash in.

After all, Twitter itself -- started as a side project in March 2006 -- has yet to figure out how it will make money from the millions of Tweets flowing through the service each day. At this point, Twitter is just trying to keep up with its growth by offering a stable platform for users.

And while chatter about Twitter's future business model is the subject of endless speculation on blogs and news sites, that's not stopping other entrepreneurial-minded folks from participating in what Denton described as a "land grab."

Some venture capitalists also see opportunity, while others remain cautious.

"Twitter has created a paradigm shift in communication and information discovery by combining various aspects of social-networking, blogging, instant-messaging, e-mail, and search," says Madrona Venture Group's Ayush Agarwal, whose been spending the past few months investigating new ways to create businesses around Twitter.

The Seattle venture capitalist, whose been working closely with Twitter application developer Damon Cortesi, creator of apps such as TweetStats and My First Follow, said that Twitter is part of a much larger trend of what has become known as "real time search."

That's the idea of creating a way for people to discover information as it happens. The flood of information on Twitter after the disputed Iranian elections served as the most recent example of the power of real time search, creating a valuable source of information for those looking for answers.

And while that is one high-profile example, Agarwal said it is "still early days for Twitter."

"There are many opportunities for extending and improving Twitter's functionality, many of which have the potential to create substantive economic value for businesses and consumers," he said. "As a result, we are starting to see more and more developers and VCs looking into this space."

For example, Madrona and others believe there are interesting parallels between Twitter and the way the Internet search business evolved. The key now, he said, is to bring more relevance to the discussion points on Twitter.

"...As the Tweetosphere gets more and more noisy, services which help users isolate the signal from the noise will create a lot of value for users," he said

But not everyone is a believer that the Twitter platform represents a compelling opportunity. 

"I am quite skeptical that one can build a valuable, large scaled and sustaining business on top of someone else's core platform offering," says Bill Bryant, a venture capitalist with Draper Fisher Jurvetson. "It doesn't matter if you're talking about Twitter, Facebook, Salesforce, the iPhone, Windows, Cisco ... the platform will over time absorb the best and highest valued extensions, additions, features, services in its own drive to add value to the broadest set of customers."

A perfect example of this can be seen with the introduction of the new iPhone 3G S. 

Apple, which has opened its platform to thousands of developers, took some of the most popular apps created by outside developers (for example, the landscape keyboard and voice memos) and embedded them into the 3G S. 

And while there may be an occasional break out company that gains momentum on the iPhone, Facebook or Twitter, Bryant thinks those won't happen with much regularity.

"There will be an occasional success story - see Zynga on Facebook for instance -- because the platform vendors need to encourage third parties to continue to build on their offering," he said. "But Zynga is one of (about) 35,000 Facebook applications."

Those are steep odds. Nonetheless, entrepreneurs think it's worth a try.

Appature, a Seattle provider of online marketing tools to healthcare companies, earlier this month introduced Chatterfly to help its customers better manage their brands on Twitter and find relevant information.

At first, Chief Executive Kabir Shahani said he wasn't quite sure if building a Twitter application was worth the company's time. "There is definitely a sense that these things come in waves," he said.

But Shahani became a believer after seeing some of the success that Dell and Comcast reported in terms of interacting with customers through the microblogging service.

"We wanted to get out in front of that, and be able to really help our customers understand the value that they can get out of Twitter from a marketing perspective, and not be left in the forest if you will," he said. "Twitter is what people are asking the most about -- it is the new kid on the block and people are trying to figure out if there is some business value behind this."

Denton, the project manager of Twibs, which is bankrolled by VMware executive Richard McAniff, also is trying to figure out the business value.

Denton

As recently as a few months ago, Denton said that many of the people building Twitter applications were just "hobbyists" who were looking to create something cool. But things have changed recently, with venture investors and developers really starting to think through business models.

One thing that's driving that experimentation is the openness of the platform and -- at least up until now -- the lack of interest from Twitter itself to create new applications, said Denton.

"They are really just giving you a network to build software around," he said. "And if you come up with a home run travel service on Twitter -- it's yours. They are not going to come back and want 10 percent."

That sort of openness is driving some of the entrepreneurial energy that we see today. And Denton thinks it will accelerate as Twitter applications move out of that hobby stage.

Denton has been impressed that Twibs quickly attracted 14,000 business users and more than 50,000 monthly unique visitors with no marketing.

But that's just the starting point of what the Seattle startup is trying to accomplish. Now, he said, they are getting more serious about building a new enterprise-scale analytics application that corporate Twitter users will actually pay for.

"Everyone has thrown a little mud at the wall," said Denton of Twitter application developers. "But now ... they are taking a different approach -- they are sitting down and looking at Twitter like they are rolling out a real product."