Michael Henke

This plugin will create a Flattr button in you RSS feeds item. Feed readers whith support can then show the button below the text, so that readers can Flattr directly from their RSS reader.
Flatt RSS plugin requires an account at flattr.com!

Flattr RSS

This plugin is including the Flattr button in your RSS/Atom feed.
There are some more options to extend Flattr functionality like optional autosubmit  …

zhenech

With Sexy RSS Footer you can add everything you want to the end of every feed entry. 
Backlink to the site? Sure. 
Number of comments? Sure. 
Flattr link? Sure. 
Something totaly different? Yepp, even that!
Suggestions for more replacement variables highly welcome!

Sexy RSS Footer

Sexy RSS Footer enables you to add any possible content at the end of every feed entry. This includes variables like number of comments, author etc.

Flattr RSS vs Sexy RSS Footer