'Free' PDU for PMI re-certification

There are many opportunities to gather PDU's for free - see example this article by Patti Gilchrist on Projectmanagement.com (You might have to register before you can access the full article.)

She initiate her article as follows:
 

1. So let’s start with the easiest and the most obvious. You are a PM, right? Did you know you can get credit for just showing up?! If you are currently employed as a project manager, then you qualify for PDUs under Category F: Work as a Practitioner. You can claim five PDUs per year (and 15 PDUs per cycle) for being a practitioner of project and/or program management services.Note that this category (Category F) is part of the Giving Back to the Profession category, which includes Categories D, E and F. You can claim 45 out of the required 60 PDUs per three-year cycle by giving back to the profession.