today i learned that you can tell google to search on a TLD. which is especially fun on TLDs like .mil or .gov
for example, here's every mention of anime on indexed US military sites by using the query site:mil AND anime, or every mention of blåhaj on official educational facility websites
You can refine for a good number of other things, too. Filetypes are another interesting one. PDFs on government websites mentioning whatever keyword you'd like. Txt files matching oddly specific phrases.
There's even an interface for it. Have fun.
