After giving it a bit of thought, I decided to reactivate my flattr account. Since the flattr API improved a lot since flattr's early beta days, I thought it would be nice to integrate the auto submission feature with Serious, my current (ruby based) blogging engine of choice.
This blog post will discuss the paramaters that can be used to automatically add the buttons.

The first thing to do will be inserting the javascript part of the integration into our /views/layout.erb file. This file contains (among other things) the header that is part of every page. This code doesn't need any customization and can just be copied into the head section of the HTML

<script type="text/javascript">
/* <![CDATA[ */
    (function() {
        var s = document.createElement('script'), t = document.getElementsByTagName('script')[0];

        s.type = 'text/javascript';
        s.async = true;
        s.src = '';

        t.parentNode.insertBefore(s, t);
/* ]]> */

The HTML part of the API has to be added to the "/views/_article.erb" template that is responsible for diaplaying the actual content of each blogpost.
In this case, just replace the "data-flattr-uid" value with your fattr username.

<a class="FlattrButton" style="display:none;" title="<%= article.title %>" data-flattr-uid="rb2k" data-flattr-category="text" href="<%= Serious.url + article.url %>"><%= article.title %></a>

This should be it, happy flattr'ing