Not only does MuckRock help identify which agency has the record you might be looking for, but has a tracker to follow the grinding progress as that agency drags its feet in responding to your request.
From the Lab:
The idea was to build a service that anyone could use — a long-time journalist, a neighborhood blogger, or someone simply looking to get answers out of city hall. The value to bloggers or citizen journalists seems clear: Providing not just tools but guidance on the sometimes labyrinthian process of making document requests. But for journalists working at established media outlets, the pitch is a little more tricky. “We’ve kind of found our sweet spot right now is helping out anybody who’s at least that pro-am journalist or a community blogger,” said Morisy, who has written for the New York Daily News and Business 2.0. “But also the overburdened reporter who writes stories, blogs, tweets, and has to juggle investigations.” In theory, a new resource to help newsrooms expedite FOIA requests would be a help, particularly at a time when shrinking staff and rising demand on reporters may exclude investigative projects. In reality, experienced journalists are generally more comfortable undertaking FOIA requests themselves, if not for accuracy than to keep a story under wraps from competitors or the government itself.