Ask HN: Do you want an api to generate file preview images?

I'm trying to come up with an idea for a hackathon (hackpr.eventbrite.com) and thought it might be cool to make a service that could generate a thumbnails of any kind of file.

You send the url of a file and the service will give you the url of an image preview of the contents of that file.

I have an idea on how to do it but was wondering if you guys were interested in using something like that. What is the point of building something nobody wants to use.