Maybe I'm missing something here, but why go through the pain of rewriting HTTP headers, adding meta tags, and keeping track of a user's preferences, when you can simply use Unicode?
Yes, it's a pain to get content people to use Unicode, and old browsers don't handle it intelligently. But I've found Unicode to be a great solution to precisely this problem, freeing me from having to worry about where people are from and what characters they want to see.
Also, the meta tag only assigns the character set if the HTTP headers fail to do so. So if you always indicate the character set explicitly in the Content-type HTTP header, then you shouldn't need the meta tag.
