Flattr-on-blogger is a project mainly written in JAVASCRIPT and PHP, it's free.
Blogger widgets that puts flattr buttons under your posts.
This project adds a flattr widget to your blogger account.
A version of the index.html and send.php is hosted here: http://flattr.kejsarmakten.se/blogger (requires php)
An example blog is hosted here: http://test-flattr-blogger.blogspot.com/