"I lost many hours of sleep staying up to watch Johnny, and he was worth it," said one reader on the Yahoo message boards.
Added another: "No one will ever replace him as 'Tonight Show's' best."
Carson died early Sunday morning, surrounded by his family, said nephew Jeff Sotzing.
Web sites including MSNBC and ABC News.com, and aggregators such as Google and Yahoo, all quickly carried the news. MSNBC led its Web site with a photo of Carson, labeled "breaking news." Google News quickly listed dozens of articles. "Good-bye Johnny," a big headline on the Drudge Report read.
MSNBC also asked readers to share their memories of the longtime host of TV's "Tonight Show," via e-mail, now a common feature on Web news sites. It later added a video clip.
CNN ran a bulletin at the top of its Web site reading "Former "Tonight Show" host Johnny Carson dies of emphysema, his nephew tells CNN. He was 79. Details soon." CNN later added a story and a video clip.
ABC News labeled its report an "original story," attempting to set itself apart from the aggregation sites and others that run wire service copy. Most of the sites carried a report from the Associated Press when the news broke.
For its part, eBay listed 174 items under Johnny Carson. None of the listings had yet been updated to mention Carson's death.
When Carson retired from the "Tonight Show" in May 1992, the Internet was not a big competitor to television and print as it is today--a fact that undoubtedly would be part of a famous Carson monologue. He might have liked to poke fun at the MSNBC ad that ran at the bottom of his obituary promoting "Johnny Carson 4-video set, plus bonus--$39.95"--a result of the business side of free Net news.
Almost 88 percent of online Americans say the Net plays a role in their daily lives, for receiving news and entertainment and for communicating with friends,by the Pew Internet and American Life Project. Sixty-four percent of respondents said their routines would be hit without the Net.