Open Discussions With GetSatisfaction.com
GetSatisfaction.com is a free service that connects products and services owners with their users.
Those who have a regular/digital product or service can create an account at this site and start a community/group. They will be notified when a user joins and asks a question. Of course, one can still create a group irrespective of whether they are actually owning a product/service.

Get Satisfaction is a direct connection between people and companies that fosters problem-solving, promotes sharing, and builds up relationships. Thousands of companies use this neutral space to support customers, exchange ideas, and get feedback about their products and services. Get Satisfaction is open, transparent, and free. You’re free to ask, free to answer, and free to start a new conversation. Everyone is invited and encouraged to participate: companies, employees, customers — anyone with an opinion, an answer, or something to say.

Google launched Google Sites as part of the Google Apps suite.
This list is mainly for those who have just installed their WordPress blog. The great thing about WordPress is that it is extensible via plugins. The following is a list of plugins that covers the most common needs of any blogger.