Some time ago I released the Campaign Monitor Advanced module. A module that provides advanced integration with the excellent Campaign Monitor mailing list service. Cool stuff was available in it like support for multiple lists, automatic fetching of lists and fields from your Campaign Monitor account, asynchronous pushing of subscription and unsubscription requests and the ability to match Campaign Monitor custom fields to Drupal tokens, profile fields and PHP code. Cool huh?
Well, you'll be happy to know that all this stuff is available for more services then Campaign Monitor only. I have completely rewritten the module as a framework, called E-mail Marketing Framework, to make it work with virtually every mailing list service that provides an API to some of its functionality. Right now, out the box only MailChimp and Campaign Monitor integration is provided.