Bloggers are scoring rich paydays by turning their online diaries into books, but some publishers say the craze could fizzle out with a glut of new titles destined to yield disappointing sales.

Penguin became the latest to jump on the bandwagon when it bought "La Petite Anglaise," the memoirs of Catherine Sanderson, who was fired by her company because of her blog, in one of the more hotly discussed acquisitions this week at the Frankfurt Book Fair.

"The blogs should be almost incidental to us as publishers," said Katy Follain, publisher at Penguin imprint Michael Joseph, which bought "La Petite Anglaise."

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"We need to look at the writing itself. Her writing is so strong we signed her for two books."

The price paid to Sanderson was not disclosed, but trade publications put it at around mid-six figures, a rich advance usually reserved for bestselling authors. The book is slated for release in spring 2008. Pearson Plc owns Penguin.

"I'm not quite sure what a mid-six-figure sum is, but let's imagine 500,000 pounds ($942,700) and let's assume that non-UK rights are about the same," MacMillan Chief Executive Richard Charkin wrote on his own blog.

"It means that the book will have to sell around a million copies to earn back the advance."

Some blogs-turned-books have been hits with readers, but publishers could not recall any that had reached such a lofty sales tally.

"Belle de Jour," the diary of a London call girl, and "Julie and Julia," a New York woman's struggle to cook the recipes of celebrated chef Julia Child, both became bestsellers.

WAVE OF HYPE

But others that arrived amid a wave of hype including Stephanie Klein's "Straight Up and Dirty" and Jeremy Blachman's "Anonymous Lawyer" haven't fared as well.

Also on tap is a fresh wave of blog-based books from a waiter, a New York taxi driver, a pair of quilters and a wine connoisseur, and a handful of titles with political themes.

"I just hope publishers with deep pockets don't squash the life out of blogs becoming books," said Clare Christian, publishing director of The Friday Project, a start-up firm dedicated to combing the Internet for book projects.

"It's like the dot-com boom all over again," added Paul Carr, Friday Project's editor in chief.

"In the same way that publishers knew they needed a Web site even if they didn't know what that was, they're just buying up blogs because they're hot."

The Friday Project's "Blood Sweat & Tea," based on the blog of Tom Reynolds, a London Ambulance Service emergency medical worker, has sold 30,000 copies and is in its third printing.

Carr said they grabbed Reynolds just as he was about to sign with a larger publisher, claiming they won him over with their specialty focus after he was forced to explain what a blog was to several of the rival house's executives.