NSF Dear Colleague Letter lists International Funding Mechanisms

A recent NSF Dear Colleague letter was issued to remind researchers involved in the BRAIN initiative of funding programs and mechanisms that support international cooperation. Most of these programs are equally applicable to international collaborations in other research topics funded by NSF and bear repeating:

Who Funds What: A Quick Guide

This table (in pdf) gives an overview of the agencies (and a few foundations) that are most active in funding academic research and what types of research they fund. The links take you to the funding page of the agency (which can sometimes to be difficult to find for agencies where funding research is not a major part of their mission), not just to the agency's home page.