As website owners, it's vital that we stay on top of emerging trends and changing consumer needs - whether you simply want people to sign up for your RSS feed or you're selling mouse pads.
Mailing lists are a good way to keep abreast of important industry news. Essentially, these mailing lists are nothing more than discussion forums, mostly over email. What's important for website owners is being ahead of the curve. People can join the list and you have an instant community of users that share your business interests. While it's not advised to start dropping your business name all over the place, you can certainly gain an edge by staying on top of your consumer's interests and changing needs. It's a simple way to network within your industry and you may end up driving traffic to your site by becoming a respected member of the new "community."
Yahoo! Groups is a quick and easy way to get started. It's easy to navigate and there are thousands of discussions taking place. Of course, Google has a substantial group userbase as well, found here.