A recent Pew Internet Blog Report surveryed bloggers on a variety of topics. I found the following to be particularly true of my own motivations (quoted from NY Times coverage):
Despite a potentially vast audience in cyberspace, the Pew project found that 52 percent of bloggers said they blogged mostly for themselves. When asked for a major reason for blogging, 52 percent said it was to express themselves creatively and 50 percent said it was to document and share personal experiences.
