Endangered Language Database does, is collect and document those threatened languages. As they themselves describe their mission:No technology can keep a language from going extinct. Languages require a context of culture that no electronic tool, however sophisticated, can reproduce. But what it can do, and what Cambridge University's
"Researchers at the World Oral Literature Project have compiled a database of language endangerment levels with references to collections and recordings of oral literature that exist in archives around the world."
Ethnologue is a tremendous resource, a catalog of the 6,909 known living languages on earth. The Red List is the product of applying "a set of internationally agreed criteria for classifying species extinction risk to languages."
The database was built with an open source PHP application called DaDaBIK.
The interface allows a user to search by language name, number of speakers, region or country or source. I looked for languages with under 500 speakers and got 1,659 records returned, including the languages Abhaz and !Xoon.
I searched again for a language I've written about, Sahaptin, spoken by American Indians of the Confederated Tribes of the Warm Springs Reservation in Oregon.
This language was listed but there were no resources listed for it.
The database is pretty slow and far from exhaustive, but it is a good start toward documenting something desperately in need of documentation, not just as a kind of electronic tombstone but as a resource for those on the frontlines of language (and therefore culture) preservation and rehabilitation.