Feed Filter can be configure to manipulate the feed served to some specific IP addresses.
I used it to send reduced content with no images, back links and copyright notices
to automated blog network that was republishing my contents.
More, the plugin can "delay" the feed seen by specific IP: this is useful to have
you article titles published before sites or networks that republish (legally or not)
your feed items.
I wait for users comments on
www.satollo.net/plugins/feed-filter.