Imagine what it was like to be Dr. Kleenex. You invent a modern miracle, an inexpensive paper handkerchief, and suddenly you become the person to blame for America’s disposable culture, or praised for a more convenient life.

There never was a Dr. Kleenex – the product was created by a team of researchers in Kimberly-Clark laboratories in the 1920s. But there is a real Craig in Craigslist, Craig Newmark, and lately he has been looking at life beyond his little list that has become one of the most popular U.S. Web sites.

It is also a site that is deeply tied up with the fate of newspapers – indeed, many in the newspaper industry blame Newmark by name for the downturn in their classified advertising business – as well as real estate and the Internet-fueled marketplace.

An ardently no-frills, user-sensitive site, Craigslist has, in the estimation of the company’s chief executive, Jim Buckmaster, generated more than 600 million free classified listings for people. (Even though nearly all listings on Craigslist remain free, it has added modest fees for job listings and real estate brokers in some big cities, and it generates an estimated $80 million to $100 million in annual revenue from those fees, with a staff, based in San Francisco, of 25, including Newmark.)

In the United States and beyond, Craigslist is digging even deeper into classified ad markets. Once, the announcement that Craigslist was expanding meant adding new cities like Miami, Minneapolis and Philadelphia. Today it means towns like Janesville, Wisconsin (population: 60,000), and Farmington, New Mexico (population: 38,000), as well as Cebu, the Philippines, and, by personal request of Newmark, Ramallah in the West Bank.

In the face of this expansion, Newmark now wants to become more of a public figure, capitalizing on his success to promote personal causes, which include supporting the presidential campaign of Barack Obama and financing investigative journalism – not, he insists, to compensate for the alleged damage Craigslist has done to the newspaper business, which he calls ”an urban myth.”

Newmark used to spend two-thirds of his time working on customer service issues (including notifying an Internet service provider about a scammer on the site the very minute before a reporter showed up one Friday morning), he explained, and one-third on ”founder issues,” a catchall term that he uses for his public-minded work. That ratio, he said, would now be half and half.

But before he can extricate himself from customer service, Newmark will have to extricate himself from the quickly growing business and legal complexities that surround Craigslist, a laid-back operation that is bumping into tough-minded competitors as it continues to grow.

Newmark’s name is the first one in a Delaware lawsuit that accuses him and Buckmaster of boardroom chicanery, which they emphatically deny. Their accuser is eBay, which became a minority shareholder in 2004, with roughly 28 percent of the company.

The lawsuit resulted from eBay’s decision to introduce a rival online classified site, Kijiji, in the United States last year. Kijiji already is the market leader in Canada, Germany, Italy and Taiwan.

EBay alleges in its complaint that after the creation of Kijiji, Newmark and Buckmaster plotted in secret to dilute eBay’s influence in the company, including to deprive it of its board seat. The lawsuit asks the Delaware court to reverse those provisions.

Craigslist is expected to respond to the complaint this month, but on its official blog, it offered an assessment: ”Sadly, we have an uncomfortably conflicted shareholder in our midst, one that is obsessed with dominating online classifieds for the purpose of maximizing its own profits.”

Despite its success, Craigslist still prides itself on its grass-roots instincts – including harnessing its users to identify and block bad actors on the site. Even broad strategic decisions, like which areas to expand to, are described as merely reflecting user requests made at online forums at the site.

As was made public in the complaint, Buckmaster last year wrote to Meg Whitman, then the chief executive of eBay, to say, ”We are no longer comfortable having eBay as a shareholder, and wish to explore options for our repurchase, or for otherwise finding a new home for these shares.”

In an e-mail message of its own, eBay emphasized that the two would remain joined together: ”We would obviously prefer to see this resolved without litigation. With that said, we will only accept a resolution that preserves our rights and the full value of our investment in Craigslist. We will continue to act openly and in good faith as a minority shareholder.”

The competition between the companies is also heating up outside the courtroom. Ebay has recently sent out e-mail messages to its users promoting Kijiji, and Craigslist in the past few weeks has added 120 cities, half of which are overseas, where Kijiji is dominant.

This time of expansion comes as newspapers are experiencing a steep downturn in classified advertising, greatly magnified by the cratering housing market and a weakening U.S. economy. Print classified advertising declined 16 percent last year to $14.2 billion, according to the Newspaper Association of America, below the level for 1996, even without adjusting for inflation.

In this straitened market, Craigslist becomes shorthand for the threat online advertising outlets pose to newspapers, something Newmark denies.

Buckmaster backs up that argument by pointing out that Craigslist has no salespeople and has never sought to win over newspaper advertisers, in contrast to larger companies like the job-listing site Monster. ”That to me is a direct attack on newspapers,” he said. ”We put a service out there.”

”There are bigger things that have been more problematic for newspapers,” Buckmaster added, including the loss of circulation and basic mismanagement. ”Newspapers have an enormous amount of debt. That is not something that can be laid at our doorstep.”

Clayton Frink is the publisher of The Capital Times in Madison, Wisconsin, where Craigslist arrived in April 2005 and which last month stopped printing a daily newspaper for a new Web-print strategy.

”They have ads we would have had once upon a time,” he said, but added that his staff members did not consider it ”No. 1 or No. 2 or 3 of Web sites that hurt our business.” The bigger enemy, of course, is the changing world, he said, noting that large employers routinely used to buy one and a half pages of ads for job listings and that ”now they put in a small ad saying to see their Web site.”

”What Craigslist does well is build a community and a feel of a community,” Frink said, adding that ”building communities is going to be critical for any online product, whether a newspaper or not.”

Also, Craigslist no longer sneaks up on local newspapers. Sammy Lopez, the publisher of The Daily Times in Farmington, said: ”We’ve been kind of watching them. You can get on Craigslist and see if people have been requesting a site. I asked someone to look at that four or five months ago, and saw that they had.”

He said the knowledge that Craigslist would be arriving someday led the paper to improve its online presentation of classified ads, creating more categories for the ads and clear entry points on the site. He pointed out that a vibrant classified ad section was not only a revenue source, but also a reason for people to buy the paper and visit the Web site. The paper also allows free ads for any item less than $100.

Newmark is an unapologetic believer in the power of technology to improve life – whether in the blogging he does for Obama, a visit he recently made to Israel where he argued in favor of microloans and technological innovation to build up the Palestinian economy and increase the chances for peace, or the use of online tools to make government more transparent.

He promotes these projects on his personal blog. As of the past couple of weeks he has been writing posts on the Twitter networking site, too.

Newmark is also involved with Web sites like factcheck.org, prwatch.org, newstrust.net, sunlightfoundation.com and publicintegrity.org.

Newmark has not followed the usual path to Silicon Valley philanthropy – create a successful Web site, sell that Web site either to a larger company or through a public stock offering, acquire a huge pile of cash and then give away part of that pile of cash.

While not willing to discuss his personal wealth from Craiglist, he states the obvious when he notes that he could be a lot richer if he wanted to be.

”We know these guys in Google and the eBay guys and they are not any happier than anyone else,” he said. ”A lot of money is a burden.”