I create videos, mainly focused on agile techniques, that I distribute online. Currently all of my videos are on Pluralsight but I've signed deals to start branching out to other distributors with new content in 2015. http://www.pluralsight.com/author/jeremy-jarrell

Currently the videos generate about $3,500/month in revenue. There's little out of pocket expense for the initial production of each video (stock imagery, reference books, etc) and no ongoing expenses after production is complete.

I started out just focusing on topics that I was interested in but didn't have a lot of success. Once I started approaching things as a business my return improved dramatically.