Some blogging statistics by Rick Bruner. Highlights:
in late February 2004, the Pew Research Center released a study based on phone surveys of 2,515 online adults it had conducted a year earlier, which found that 2 percent of respondents had their own blogs. Based on Pew’s estimate that 126 million U.S. adults are online (as of December 2003), that works out to 2.5 million U.S. adults who blog (note that Perseus’ 4 million estimate included blogs worldwide.)
That is more, Bruner says, than read USA Today per day. Also, a nice site about blog advertising and rates. Also, a company weblog about advertising and the business of weblogging.