Other International Languages: Linguistic Diversity
700 reasons to study languages — This is a British site, so for "sixth formers" read senior high students, etc. But it's full of good ideas.
Exploratorium Magazine — Language — "Where do languages come from? Learn about the origins and development of language. Hear from linguist Merrit Ruhlen how language is studied and classified. Examine words from different languages to learn how they are related."