While Streller admits he hasn’t ruled out acquisition, by Twitter or anyone else, as a business plan, his four-employee company is expanding. They are currently developing SocialPing, an application that helps businesses track what’s being said about them in real time on Twitter.

For Twitter aggregators like TweetDeck and Twitterrific, expansion beyond Twitter is a must, says Josh Bernoff an analyst with Forrester Research, because all it takes is Twitter to acquire one, expand it, and bury the rest. Bernoff holds up the site Summize, a Twitter search engine, as a prime example.

“There used to be several Twitter search sites like Summize,” Bernoff says. “But Twitter bought that company. If you go to search.twitter.com you are going to Summize. But it’s better now because it’s part of Twitter. There were other Twitter search sites, but no one uses them any more.”

For Gedeon Maheux, a principal founder and designer with Iconfactory, the creators of Twitteriffic, a desktop client that aggregates tweets, keeping the Twitter app as a popular yet ancillary product to their main revenue stream is key to long-term success.

Iconfactory’s core business is icon design for corporate clients for the Web, Mac, Windows, and mobile devices—“Anything you can think of that needs an icon, that’s what we design for” says Maheux”—but they also design software, and it’s becoming a big part of their business.

Twitteriffic was initially created for the staff of Iconfactory to personalize and easily aggregate Twitter feeds into one place. The company unveiled a public version at the 2007 South By Southwest, and that’s when it really took off. “Twitterrific was the first time a large group of geeky people could get together and network about Twitter’s potential,” recalls Maheux. “The downloads on the Mac side exploded after that.”

At present, the company has no interest in expanding Twitterific beyond Twitter, Maheux says. “It was made to work with Twitter, not Facebook or MySpace or Flickr. Our focus is on Twitter.”

Maheux says Iconfactory is not looking to be sold and that they want to keep its independence. They saw how Twitter competitors like Jaiku were bought, but soon after acquisition, stopped developing their products. Twitteriffic is Iconfactory’s bestselling property, Maheux admits, but the company is not just defined by that one product.

“Would it suck if Twitter built its own version of Twitteriffic?” Maheux asks. “Yes, it would be bad, but it wouldn’t be the end of the world.”

Some companies, though, are less wary. When asked what their business model was, Chika Watanabe, vice president for business development for Naan Studio, the creators of Echofon (formerly Twitterfon), an iPhone and iTouch mobile application that lets you follow and post tweets to Twitter, shot back: “We don’t know. You tell us.”

Launched as Twitterfon two years ago, the company’s name change reveals that they’re worried about over-dependence on the big fish. Free and “professional” paid versions of the app are available, and the company recently launched both Firefox and Mac OS extensions of the app.

“Twitter is not the only medium for people to communicate,” Watanabe says. “There are other platforms coming, and we are planning to add other things. That’s the reason why we changed our name to Echofon. It’s not just going to be Twitter. It’s going to be one application that enables users to use multiple communication media.”