They're not hard to set up, but they can be invaded by spammers if they are not frequently monitored. They are useful for encouraging communication among like minded people, but don't set one up thinking you can then walk away from it.
Here are some alternatives:
A forum, also known as a "bulletin board", is a means for website visitors to post questions and answers, or to have discussions. They're very popular for sharing expertise and getting technical support. A person, for example, needs to know how to plant a tree, so she goes to a gardening forum and posts her question. If it's a popular forum, or one that's actively moderated, she will get an answer within a few hours.
If you have a regular website, you may find your hosting company offers you the ability to set up a forum as part of their offering. iPage, for example, provides blogs and bulletin boards as part of its basic hosting fee. Usually, what the web host is offering is a free program called phpBB3. The phpBB bulletin board doesn't require programming knowledge, but it can be a little complicated to set up. Make sure you check the option to have an email sent to a subscriber's mailbox before they can register. Otherwise, you'll be flooded with spam.
Podcasting is a way create and share audio on the web. Want to be an Online Radio Star? Join BlogTalkRadio, it is free and easy to get started! Broadcast now.. Like a lot of tools, BlogTalkRadio is free if you don't mind ads.
Frequently, simple chat is used now as part of a larger website, usually for live customer support. LiveChat offers live help chat. It's great for a company whose customers need help selecting or configuring their merchandise. It's also an efficient way of offering advice or counseling, since a counselor can handle more than one client at a time, answering one while another is typing a question.