Post2Mail plugin allows you to automatically e-mail selected people when a post is published on your blog. Also useful for alerting an administrator when a post has been published on the blog. Configuration is done in the post2mail.config.php file which has comments to get you started.
Some of WordPress user needed a plugin to send an e-mail to a mailing list whenever a post was published to the blog. Here is a modified version of the Post2Mail plugin which can email the post to a mailing list or email address.