Yes they do.
In re-doing my website, I've tried to stick with public domain data sources for my information, that way I don't have to worry about infringing on someone's copyright etc. The NWS/NOAA/NASA/SPC/HPC/NCDC sites (and on and on) have so much stuff that I'm still discovering things!
Sometimes they make it easy to do, other times not so much. On top of that, I try to find better ways to display the same data, either by making it easier to find the data, or by coming up with a different interface so you don't have to go through so many pages. It's not always easy to do either.