In an article released today, Brian Womack of Bloomberg.com reports that Twitter is exploring revenue models that include charging businesses to use Twitter, rather than seek additional venture capital funding. The company has already raised $22 million in funds, but with the current state of the economy, Twitter CEO Evan Williams says, “the VCs have the money, but they’ll just negotiate harder” wanting a larger return on investment.

According to the article, Williams said that Twitter may charge businesses to reach users. This may include opt-in coupon promotions, market research and display advertising. “I want to manage things so I don’t have to raise money in 2009,” Williams said.

The article also states that “global visitors to Twitter rose almost fivefold to 5.57 million in September from a year earlier.”