If you have a website and you're selling stuff through it, you might want to add a Discussion Forum so your customers and potential customers can interact with you and others.
A discussion forum is something like the tagboard on this blog but much more advanced. You can have sub-forums and topics within those forums. Depending on how much leeway you'd like to give others, you may allow them to post new topics, run polls, etc. For an example of a really sophisticated forum, check out the Playwrights' Forum, owned by Stageplays.com
A search for "forum" or "discussion forum" should give you some good options. I use the free phpbb forum from mfbb. It's an open source software and you can either host it on your own site or use the free sitehosting from mfbb if you'd like to make a test forum first.
I suggest you use the free hosted option and test the site with the help of a few friends before you host it on your own site and make it "live". You'll get a feel of administration and learn to set up membership options, posting privileges, etc.