CGI Resource Index - a source for many kinds of CGI scripts. They are a great way to keep your visitors informed of new content or products on your site. Some articles I have read point out that e-mail advertisements are more powerful than banner advertising. Having my own newsletter with more than 6,500 subscribers, I can vouch for this. Every time I send out an issue, traffic to my site spikes.
Mailing lists are a great way to network on the web.
I suggest that you join several mailing lists that are directly related to the content on your site. You can become part of a community of people with similar interests. When appropriate, you can mention your site. For example, if someone needs help or information that your site can provide, you can reply to that person's message. However, to avoid any problems, be careful not to SPAM the list and to follow all posting rules.