Just came across a nice gem: a center for advanced research into what is known as "language acquisition".

From Website

The Center for Advanced Research on Language Acquisition (CARLA) is one of the U.S. Department of Education's Title VI National Language Resource Centers, whose role is to improve the nation's capacity to teach and learn foreign languages effectively.

Research & Programs

CARLA is engaged in a number of interrelated research and program initiatives related to second language teaching, learning, and assessment.

Professional Development

CARLA supports the professional development of second language teachers through an annual summer institute program and a wide array of international conferences and regional seminars.

Resources

CARLA offers a number of resources to language teachers including a battery of second language proficiency assessments and a working paper series.

Of special note are the resources page, resources for teachers and the database of less-commonly taught languages instructional materials.