The goals of the Less Commonly Taught Languages* (LCTL) Project sponsored by CARLA are to help advance the teaching and learning of LCTLs by encouraging people to study LCTLs, assisting LCTL teachers in developing high-quality teaching material, and helping LCTL teachers cooperate and communicate.
*by Carla's definition, LCTLs are any language except English, French, German, or Spanish.
CARLA: http://carla.umn.edu/lctl/resources/orgs.html

This page contains a list of organizations, with contact information, for both specific languages and LCTL teaching in general.
LRC: http://nflrc.msu.edu/login/scripts/materials.php

This page contains searchable resources/materials online provided by 17 Language Resource Centers. The materials could be searched in terms of language, levels, skills, audience, categories, and general formats.
CAL: http://www.cal.org/topics/fl/heritage.html

This page features Alliance for the Advancement of Heritage Languages and resources for heritage languages, which are typically related to less commonly taught languages. The web page of Alliance contains, for example, Language Program Profiles, Heritage Voices Collection,
STARTALK: https://startalk.umd.edu/resources