TrackEngine Webmaster - Automatically emails content updates to your visitors whenever you publish new content to your page. No need to maintain mailing list and customer preferences. - http://webmaster.trackengine.com
Lurker - An open source mailing list archiver. It includes an integrated search engine and supports MIME, GPG, and chronological threading. Designed for large archives (>4GB). - http://lurker.sourceforge.net/