SAN FRANCISCO  As the newspaper industry and its classified advertising business wither, one company appears to be doing extraordinarily well: Craigslist.

The Internet classified ads company, which promotes its “relatively noncommercial nature” and “service mission” on its site, is projected to bring in more than $100 million in revenue this year, according to a new study from Classified Intelligence Report, a publication of AIM Group, a media and Web consultant firm in Orlando, Fla.

That is a 23 percent jump over the revenue the firm estimated for 2008 and a huge increase since 2004, when the site was projected to bring in just $9 million. “This is a down-market for just about everyone else but Craigslist,” said Jim Townsend, editorial director of AIM Group. The firm counted the number of paid ads on the site for a month and extrapolated an annual figure. It said its projections were conservative.

By contrast, classified advertising in newspapers in the United States declined by 29 percent last year, its worst drop in history, according to the Newspaper Association of America.