Summary
The Linguist List, from Eastern Michigan University, has an amazing list of language links that just couldn't go unmentioned. Included are links regarding linguistics, endangered languages, natural languages, constructed languages (conlangs), writing systems, language meta-sites and language families.
From Website
This area of the LINGUIST list contains information on languages and language families, plus links to websites devoted to natural and constructed languages, to writing systems, and to language resources, e.g., dictionaries.