Jeremy Felt

In some cases, it’s necessary to provide a summary of each post in your primary RSS feed while still syndicating 
your content with full text to various parties. Dual RSS Feed Key allows you to enter a secret key to use with 
your RSS feed to display a full text version of a site’s feed to those who have the key.

Dual RSS Feed Key

Provide a "secret" full text RSS feed on WordPress sites with summary RSS feeds enabled.

alaingg

Simple plugin that allows to include the images into your wordpress rss, rss2. 
The plugin use the post/page thumbnail or the firt attached image to the post/page gallery. viste the <a href="http://web-argument.com/2008/11/09/wp-rss-images-wordpress-plugin/" rel="nofollow ugc">plugin page</a> for details.

Dual RSS Feed Key vs WP RSS Images