So I just had this idea today and I haven't really tried it out, but I already know it works and I'll explain why.
I have a number of courses on udemy.com. I've made a few thousand dollars with them...BUT I've actually made more money sending offers to my enrollees aka my "list" through course announcements.
Well, there are dozens of other courses on udemy currently with thousands of enrollees. If you're looking to promote a particular offer or product simply shoot a message to the course owner and see if you can offer something of benefit to them or what they would charge you to send out an offer to those enrolled in their course.
Rinse, lather, repeat.
Like I mentioned before, I've actually made two or three times MORE money off the people subscribed to my courses than what I've made from selling the actually courses.
Go out there, take action, and make some money people
** Another thing you can do is create your own course, list it as FREE, which will attract quite a bit of enrollees and then charge to mail out to the list. Gotta get creative and think outside the box people. There's tons of ways to make money out there.