If you are an expert in your field then one great way to make an additional income stream is to become an online consultant for that niche. You can now easily create a website or blog and market your consulting services on it to potential clients.
Small business owners and big companies require experts in their field and the trend of outsourcing work has also increased drastically. By marketing your services you can establish yourself as a go-to person in your niche.
It may take a lot of time to establish yourself and build a reputation, however, once you do the potential is endless in the consulting business.