This is the source code for sfhacks.com, a comprehensive list of all the upcoming hackathons I could find in the San Francsico bay area. These are scattered across a bunch of different places, and my friend Shenil and I wanted them all in one place.
Every day, a scheduled job pulls down listings from Eventbrite, Meetup, Devpost, and a few other places, filters out the new ones that look like they might be hackathons, and adds them to a list in my admin UI. From there, I manually review the listings and look up more info about each hackathon, then input that into the site. It's not a very fancy process technically, but it ensures that I don't end up with any duplicates or irrelevant listings.
This isn't the best Ruby code in the world, but it's under the MIT license so you can do what you like with it. The most useful part might be the set of scrapers I've written for various sites.
Go ahead and make an issue or PR!