These are the very people whom new writers turn to for help. So pick your communities carefully and prepare for the worst. If you're lucky no one will attack you, but eventually most people get involved in flame wars. Name visibility also comes from providing content to Web sites. Not your Web site, but other people's Web sites.
Professional authors balk at the idea of providing free content.
They have attacked the idea in more than one forum. On the one hand they are making a living from their writing. But unfortunately if you're serious about building name visibility on the Internet you have to accept that most comercial Web sites are not making money. They cannot afford to pay people to write for them, beyond their own staffs. Yes, there are thousands of sites which do pay.