The easiest $5k/month business I've had was selling freelance coders to IT companies.
IT firms are booming in my country, and most of them have more demand than what they can supply (they don't have enough coders).
A lot of these firms would then proceed to find freelance coders for some projects where they don't have enough in-house people to work on them.
I used to find, train and manage freelance coders for these firms. Took a good commission from each.
I helped to ensure that the companies don't have to spend time finding a 'good enough' freelancer, as I've already gone through the 'bad ones'.