Events. Those are hard to put together, but yes can make some good money.
Now, you have to fork out a bit to start but then can make it big.
To do such a thing, you need to really plan it out. Look at the pros and cons and make sure you work under a budget that you can work with to start. Know who you will aim and what kind of product will generate some revenue.
I've worked with event organizers before, it's a hard thing in any scale. Just make sure you know what you will get into to do such a thing.