I won't call it revenue. But try mining. I know. Is mining still profitable? Well yes but not as much on 2017. If you invest around $2000 in making your'e own rig you can mine around $200 per month which is still reasonable. So you can regain your capital after 10mo. Which is not bad right?
mining is still very profitable but it requires large capital...
to make $ 200 / month the mining you run must be in the medium category, it is difficult to get to large profit > small capital from mining. mining can be made a side business and we can do other businesses that are still related to the internet such as being a freelance writer or content builder.