What are some types of businesses that can started that help cities recover from natural disasters while at the same time generate some revenue?
The only one that really exists like now is something like Watsi, which helps raise money for people's medical issues. They are a non-profit though, not a for profit business.
My intention is to create something that helps people and at the same time can generate some revenue -- so it's sustainable over the long term.
The trick with what you're trying to do is that once a natural disaster has happened, you don't want to be seen as trying to make a profit. It will look like you're taking advantage of people in need, and it won't look good from a PR standpoint.
I think if I were going into this area (keep in mind that I'm not; it's not really my thing, and so take what I say with a grain of salt) I think I'd maybe try a two-pronged approach. I'd try to sell things for-profit well in advance of the natural disaster (think things like 72 hour kits, power generators, whatever) and then tell people that X% of their sales goes to aid people in natural disasters. Then take that money and spend it to help out when things do get bad somewhere. Because you're around, genuinely trying to help, and can possibly be handing out branded supplies (branded water bottles, etc.) your name will get out, going a long way towards helping you market.
I honestly couldn't tell you if this approach could really be effective. And I know my answer is aimed at consumers, rather than government entities. So you might have to adapt that to fit what you're really aiming for. But that's about where I'd aim if I were looking to get into this particular market.
I agree on some of those points made by rbwhitaker. But lets look at it from a core business perspective: you're actually asking a really vague question here, as there is so many kinds of natural disasters and even more ways to deal with the aftermaths of these.
Next thing is, like mentioned above, the issues of funding, if you want to do this strictly for the money, is that you're not gonna get a community behind you. If this is the case, I would focus on creating products/solutions that are needed to cover basic needs, and are better than the current ones (nutrition, water, shelter, etc), and sell them directly to the ngo's.
If you wanna do good while making money, which is a thing we should all aim for in some way, then I would focus on one area (like Asia), and one problem (like housing), and then think of a better solution than the current one.
Eg: There is a tsunami and/or earthquake here in the Philippines. Some ngo's will come in and provide basic stuff like food, water and immediate shelter. But after that the people will need housing. Figure out a way to provide new homes (like shipping container turned to houses), calculate a solution there is cheaper and faster than how it's done now, build an infrastructure around it, and create a peer funding community, where people can see what exact family and house their money is going to, which will make them more inclined to get their credit cards out. This could also work with small peer funded business loans to the fisherman who lost his boat etc. Basicly see what is needed, come with a better solution and build a community around it. You can then take a small percentage to keep you going, but it's not really a business model, where you can (should) get rich.