First of all, congratulations on the success of your initial project! I'm impressed by Chattie's list of places to take things next, were you so inclined. If I were a young person who wanted to make a business out of it, they are great suggestions. Somewhat obvious, but a nice complete list of 'em that I may not have all thought of myself.

As a retired person (you, and soon me), and assuming you have not need to monetize, I would state the obvious: Do whatever the hell you feel like doing! If you have time on your hands, maybe starting an online discussion group would be a fulfilling way to share your expertise and fill your time, without putting in a whole lot of effort. If you enjoy face-to-face, maybe offer seminar at a local community center and see what interest you can drum up. That's about all that would appeal to me in retirement.