Do you love to write? Are you an expert in a certain field? Is there a topic that you are particularly passionate about? People love the ability to carry knowledge around with them on their phones, tablets, laptops, and Kindles! Making eBooks is an excellent way to get your work out into the world and make a buck on the side. In fact, self-published eBooks account for 22% of all eBooks purchases in the United States (source). In time, writing eBooks could even replace your 9-5, but you’ll need to find a place to market and sell your work where it will get maximum exposure.
Live in a destination where travelers frequently visit? If you love meeting new people from around the world and also love the city you live in, starting your own local tour company is arguably the best business idea that will give you both of those perks. Take a unique spin on your local tour business like Erik from Vantigo. He was starting his VW van tour business in San Francisco as just a side business idea while he was still working a full-time job, and grew it to being a sustainable source of full-time income before quitting—now he's running a multiple van tour company on the back of what originally began as a crazy side business idea.
Renting out an extra room sounds like a pretty smart idea. App development also sounds like a pretty good idea, I found the link you left about how Benny Hsu made 30000 in 30 days quite useful. I have always been unsure on how you can start a blog but the 6-part video that you left was very helpful to understand how better. I also liked the idea of car flipping. I think it could work quite well especially here in Hawaii. I have personally found that dividend investing to be very useful in increasing income. I was also completely shocked that you can be paid to be someone’s friend. That is crazy that you found that.