Linguistic Society of America - holds a conference each January and a summer institute every other year.
Linguist List - lots of resources, including the Linguist List mailing list, computer tools (like IPA fonts), job listings, and more.
Ethnologue - SIL's catalogue of world languages.
Linguistics Data Consortium - Creates and shares linguistic resources: data, tools and standards.
International Phonetic Association
Linguistics Departments - University of Rochester's list of linguistics departments in the US and abroad.