moo-sticker-engine
To use this you will need to register a app with Moo.com here:
https://secure.moo.com/api/register.php
From here you will get a key and a secret, you need to edit the config.js and add these in the correct place.
You will also need a pack object that represents your stickers. The easiest way to get hold of this is to go through the process of manually creating a set on the moo website with the GreaseMonkey script mentioned here:
http://uk.moo.com/api/docs/pack-object-model.html
There are also details about the structure of the pack object. Add this to config.js as well. You should then be all good to go.