From concept to creation
How do you come up with ideas for a hackathon?
Innovation on the spot is hard. Sometimes good ideas strike at opportune times but often generating a concept for something interesting or useful can be quite difficult. It can be a lot of fun to play around with random concepts that might not succeed in the real world. Why not aim to create an app for a free driverless car taxi service that gets its funding by taking routes that have it's passengers pass by the billboards of the companies that sponsor the ride? Crazy, random ideas can often inspire creations that have a practical application.
I would say that there is two really good approaches you can use to plan for a hackathon.
1. Come up with an idea ahead of time. Plan it out and stick to it.
2. Base your project on the resources provided by sponsors.
Having a solid plan ahead of time is a great way to succeed. If you know your sponsors and what criteria you will be judged on you can plan a project that meets these requirements. You can always modify your plan later if you come up with other ideas at the hackathon but having a solidly planned foundation for your project will save you a lot of time in the beginning.
I have seen a number of conglomerations succeed at several hackathons. These are projects that may use several sponsor's APIs and/or hardware. These are usually very interesting and can be quite impressive when done right. The only think you will need to watch out for in this case is to make sure you don't create a monstrous concatenation of joined resources that achieves nothing. Something like that may be fun to build, to learn several companies API's, but it is not likely to win any formal awards.
Like anything, coming up with an idea for a hackathon is about having fun. Focus on what interests you and try to think about any skills you would like to learn.