[asveikau]

>> User comes in with a list of what they are OK being presented with...

> That is exactly what the Accept-Language header is: A list of preferred languages, detailing which ones work better and which ones to use as fallback, etc.

I knew about Accept-Language, but I just looked into it and I didn't realize it also had possibility for weighting of each language. I was thinking of an instance where you are highly proficient at languages X and Y, and a website has "native" content in X, and translated content in Y -- you don't want to be served Y in that case. Seems like a tricky case to get right and maybe some server code parsing Accept-Language could choke on it if not careful.