One place I have found to be a treasure trove of learning is the Adult Enrichment Project, which was created by a Girl Scout volunteer. Originally created as a supplemental training program for Girl Scout Volunteers in her Council, the AEP has been designed as a badge program for adults, particularly those who are working with youth. Each badge has achievement levels based on number of hours spent on the topic, from 3 to 40 hours.
Laura goes beyond topics that are specifically youth-oriented though, with badges for Email, Pinterest, Yahoo! Groups, etc. I promise you will find a badge program that meets your interests.