I have a friend who started a small business of TSP (Truck Service Provider) 2 years ago. He did it all on his own and did not have to invest anything. He did it by working as middleman for firms and truck owners. He seems quite successful now.
I am quite new to SN but I can confirm that the community here is full of ideas.
This time, though it may be touted as silly, I am curious to know if there are any other ideas which can transform into a startup without any initial cost.