Money can be earned and spent, saved and pilfered, invested and wasted. Not time. That's why time is far more valuable than money. The point? When you lack the luxury of time, making money online (or offline) can seem like an impossible task. How are you supposed to do that when you're working at a life-sucking nine-to-five job? While the stability of full-time employment might allow most to sleep well at night, it doesn't empower your creative juices to search for new income-producing strategies.
I have not personally done this but I would like to eventually. If you are artistic you could make artwork or handmade good such as ornaments, wallets, or jewlery and sell them online. Something that I personally would like to do is design T-shirts and sell them. Shop for anything from creative people everywhere is a great site and I have bought many things from them. If you make quality products and get your name out through Facebook or other social media you could get a substantial business going.