Blogging is one of the most effective ways for small companies to create credibility, marketing experts now think. It's a development that probably surprises more than a few executives accustomed to dread the flow of misinformation and mischief that the blogosphere can incubate.

But it has to be done right, in the spirit of blogging and not of advertising, and you can't just task the intern with the job.

Successful company blogs involve high-level staffers and the company itself has to have a commitment to an open, two-way conversation with its audience of employees, product users and customers, rivals and the curious who are just passing through.

Trust, it seems, is the dominant theme on the "Conception Connections" blog run by Alternative Reproductive Services, a Chicago-based firm dedicated to matching egg donors and surrogates with interested families.

The blog illustrates what works to build interest that potentially leads to new business. Conception Connections is transparent, making clear that it is run by the company. It engages the reader in a dialogue about issues they will find important, like compensation, ethics, legal concerns and pregnancy. It's also added useful links to other blogs related to infertility.

A successful blog "kind of opens the kimono and from a brand point of view lets people know who you are," says Rob Frankel, a Los Angeles-based branding consultant who has advised clients ranging from Re/Max to Honda Motorcycles and Sea World.

Regardless of the company size, what a corporate blog should not be, he says, is a dumping ground for press releases and other promotional materials hyping the company and its products. Reserve that for the company's web site. "That's all the stuff that nobody wants to read," cautions Frankel and other marketing professionals.

Indeed, one of the best ways to achieve credibility when your business is small is through an informative and educational blog, say veteran business bloggers. Let key debates and other important topics affecting your industry drive the content, and always provide a way for readers to become part of the discussion. Post frequently and monitor your traffic.

"It's really just information and talking about all areas of the process," says Robin von Halle, Conception Connection's president. The blog "does foster a sense of community and enlist people in every facet that we work with - parents or people waiting to be a gestational surrogate."

Tom Goldstein, a partner with the law firm Akin Gump Strauss Hauer Feld LLP, has gained a reputation as one of the leading Supreme Court litigators, helped in part by SCOTUSBLOG, short for Supreme Court of the United States Blog. He and his wife, Amy Howe, founded the blog more than five years ago when they were running a small, Washington DC-based firm.

Today SCOTUSBLOG, which is now sponsored by Akin Gump and managed by Howe and her small firm, attracts a readership of up to 100,000 on days when the Supreme Court makes big news. The blog includes commentary, analysis, links to court filings and related information on the nation's top court.

"The blog has always had a singular focus," says Goldstein. Recalling his days at his former firm, he says: "It was an important part of our credibility; it was something we could point to in our effort to get hired."