The most prolific bloggers are accustomed to banging out a steady stream of commentary. This weekend, 500 of them will dedicate a day of blogging to serve a higher cause, collecting pledges and raising funds for a variety of philanthropic organizations.Weblogs, often shortened to blogs, are frequently updated sites offering nuggets of news, commentary, photos, or any other content their creator feels compelled to put online for public perusal. The informal sites are usually heavily imbued with the personalities of their creators, known as bloggers. A number of them are joining in for Blogathon 2003, the geek equivalent of charity walk\/run\/bike events, featuring more obsessing over technical details and less sweating.Four years ago, Cat Connor found herself on a summer evening facing the dangerous combination of insomnia and a case of Mountain Dew. The Portland, Ore., resident decided to try a marathon day of Web writing: For 24 hours straight, she posted updates every 15 minutes to her Web site, Frytopia.com."It was fun, but, why?" she says, looking back. Connor had been looking for a project, though, and this one seemed to have possibilities."For the next year, I wanted to do something more meaningful. I'm not a runner or a biker, but I'm good at organizing things, and I love the Web," she said.And thus was born Blogathon. In its first mass outing, in 2001, the event attracted 101 participants who collectively raised $20,000 for the charities of their choice. This year, 545 participants have enlisted, with $56,000 pledged so far. At 6 a.m. Pacific time Saturday, they'll embark upon 24 hours of blogging, during which they've agreed to update their sites at least once every half hour. Readers can sponsor participants by offering either a flat cash donation or an hourly pledge, which they'll pay upon successful Blogathon completion to the charity named by the participant.What makes Blogathon possible is the sense of community that's developed among bloggers. News and memes spread quickly through the sites, and many of this year's Blogathon participants learned of the initiative through their fellow bloggers."Online journals and Weblogs are my primary sources of information these days - so if it's cool, current, or even remotely interesting, I probably mined it out of blogs," said James Cosby, a database manager and writer in Decatur, Ga.. He'll be a first-time participant in this year's Blogathon, collecting money for the Association for International Cancer Research.Cosby lost his older sister to liver cancer 13 years ago, and watched his mother fight breast cancer before going into remission. He learned of Blogathon through a friend's Web journal, and decided to join in."Cancer research saved my mother and tried its damnedest to save my sister. I owe something back," he says. "Unfortunately, I don't have any spare money. But I happen to have twenty-four hours I wasn't otherwise using."Blogathon's format appealed to his inner geek: "While I'm not a complete mouse-potato, I think trying to get people to pledge me for any kind of physical endurance event is a poor risk," Cosby says.How to fill the twenty-four hours is a problem all participants confront - and which several have decided to solve creatively. Connor, who is raising money for short-term aid organization Modest Needs, plans to offer a links-and-commentary tour of unusual online museums. Cosby has enlisted a friend's band to perform a set via Webcam, to which he'll be posting live links.Some participants plan to venture away from their living rooms. With the help of a camera and wirelessly equipped laptop, one blogger is planning a tour of strife zones, including a hospital emergency ward, a needle exchange, a soup kitchen, and a memorial ceremony for a peace activist killed in the Middle East. Another blogger plans to Web cast from a graveyard, with streaming video and a visit from local paranormal investigators. A "viewer's guide" posted on Blogathon's Web site, Blogathon.org, includes a rundown on planned activities.Running Blogathon is ballooning into a full-year planning project, Connor says, with much of the work going into community-building features. Chat rooms have always been a part of Blogathon, but this year, monitoring teams have been recruited, to surf the participating blogs and offer Blogathon readers running commentary on interesting developments. Next year, she hopes to have a map online, illustrating the locations of participants around the world.In addition to Blogathon site visitors, most bloggers will also have their own dedicated followings cheering them on. Houston blogger Laurence Simon has around 1,500 visitors a day to his blog, Amish Tech Support, and will be participating this year for the second time. He's partnered with two other bloggers to collect pledges for Magen David Adom, an organization providing emergency health and disaster recovery services in Israel. Last year, the team raised $3,500; this year, they're aiming for $60,000, enough to buy Magen David Adom a new ambulance.He's intense about the cause but light-hearted about his chosen fundraising mechanism. Last year, he occupied himself uploading video clips illustrating how to bake a loaf of bread. This year, he'll be firing up his breadmaker to create garlic parmesan pretzels.He'll also be breaking out the timer he used last year as a reminder to post every 30 minutes - and to wake himself up, occasionally. Other Blogathon participants will be relying on the age-old crutch of college students facing all-nighters: caffeine."I have an antique 1950s percolator. I intend to keep it running the whole time," Cosby says. "Hell, I may even interview it."