YouSayToo auto-publishing plugin for WordPress will automatically publish your posts in your YouSayToo account with credits and backlink to your blog. No changing of the blog feed settings required.
You need to register your site with YouSayToo in order for the plugin to work, at: http://www.yousaytoo.com/
Download: http://wordpress.org/extend/plugins/yousaytoo-auto-publishing-plugin/