Hello, there is a new certificate module based on certificate module, but more simple to use.
- No need to change any code to create new certificates formats;
- Full customized text, no need to change any lang parameters;
- No need to upload image files to administrations area;
http://moodle.org/plugins/view.php?plugin=mod_simplecertificate
or
http://github.com/bozoh/moodle-mod_simplecertificate
it tested in moodle 2.2.5, but i thinks it's work in other moodles versions