treeline - 9:18 pm on Jun 9, 2013 (gmt 0)
The US Government makes mountains of data available online, for free, with no copyright. Useful detailed data. Any imaginable subject.
Your website can grab this data, reorganize it, and publish it.
Lots of niches have people interested in this public data, it's just usually in a format that is a pain for a human to read, or in obscure locations, or compiled with lots of extraneous info to read around.
A simple script can get and display this data in a way human beings love. They'll check it all the time. Bookmark it. Link to it from their websites.