Once you have a well established website receiving lots of visitors you may want to run your own mailing list, newsletter, discussion list to keep in touch with visitors, and give them more information and keep them coming back. Make sure you take a look at the article E-Zine Publishing 101 before starting your own newsletter. Below are a few companies which will easily allow you to add a mailing list to your website.

eGroups - Lets you run a free e-zine or discussion list (moderated or unmoderated), with an unlimited number of subscribers and with only a two line ad appearing at the bottom of every mailing (no-ads option available). This is the service I used to previously run my newsletter with.

Elist - A free mailing list hosting service, use with caution.

Eurofreebies Maillist - They offer a free remotely hosted mailing list. With this service, you can set up a newsletter for your site, and send messages and announcements to people who sign up.

ListBot - Free mailing list, you can send out one 10KB message per day. A couple line advertisement appears on every mailing. Allows you to collect various demographic information from the people that sign up for your newsletter, a feature that does not appear in any other mailing list service. R

Liszt - Not a mailing list server, but a place to promote your mailing list, and to seek advertisers for your mailing list.

Mail Server - Free mailing list for your site, 1 banner required on your site or a yearly fee. There are no actually ads in the mailings themselves.

OneList - Run a free mailing list from this site, it looks pretty good. An advertisement appears on every mailing.

WebsitePostOffice - A free service that will allow you to add an announcement list to your site, from the people who brought you websitegarage.com.