Disclaimer: Hackathons are good, and the people who run them are great. This is not meant to reflect negatively on any of these fine events or people.
At the start of a hackathon, there's a tradition of having people get up and pitch their APIs as possible starting points for projects. These are almost always corporate APIs.
But there are lots of formats and protocols that are created in open and non-commercial ways, and there are no corporations whose mission it is to promote them. As a result they are almost never pitched at hackathons, and hacks have a distinctive corporate flavor.
This is unfortunate because usually the most fertile APIs are the ones no one owns. The ones owned by corporations tend to have big missing bits of functionality that represent the corporate hope to have a business model.
So in the future, get some community people up their pitching from passion more than profit. It'll make your event even more interesting, in my humble opinion.
Bonus: A total of 11 ideas for hacks, all building on (or creating) open non-corporate APIs.