Michael Henke

This plugin is including the Flattr button for your blog inside a widget. 
This way the button can be easily positioned in any of your themes sidebars.
Your flatter credentials are all automagically imported from the official Flattr plugin.

Flattr Widget

This plugin is including the Flattr button for your blog inside a widget.

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  …

Flattr Widget vs Flattr RSS