The LINGUIST List, the internet resource for linguists (I am certainly not biased as a former employee).
The Sociolinguistic Events Calendar, a volunteer-run Google calendar of all sociolinguistic events around the world. Not sure when or where the next must-attend workshop is? Trying to decide when to schedule your symposium so it doesn't conflict with NWAV? We can help with that!
Language Documentation and Conservation, a free open-access journal for issues of language documentation, description, revitalization, and archival. The best journal on those topics, in my unbiased opinion.
The Language Documentation Training Center, a student-run initiative at the University of Hawaii to provide training and support in language documentation to speakers of underdocumented languages.
Linguists Outside Academia, "a motley crew of self-identifying linguists with tenuous connections to the groves of academe."
Endangered-Languages, a GitHub repository of open-source computational tools for endangered and under-resourced languages, curated by Richard Littauer.