AidData is a portal for an extensive database of development assistance. Users can query the data by combinations of aid recipient, aid donor (individual countries and multilateral organizations), year, and aid purpose. The AidData project has a separate site devoted to Chinese development finance.
International Monetary Fund (IMF) Macroeconomic and Financial Data
The IMF's data library covers topics such as investment flows, monetary aggregates, economic output, commodity prices, exchange rates, public finances, financial institutions and markets, and both public and private debt. The available databases include the Balance of Payments Statistics, the Direction of Trade Statistics, the Government Finance Statistics, and the International Financial Statistics.
OECD Query Wizard for International Development Statistics (QWIDS)
QWIDS is a (relatively) accessible interface for very detailed data on foreign aid and development assistance that allows you to break down aid flows by combinations of recipient, donor, and purpose of aid.
United Nations Commodity Statistics Trade Database (Comtrade)
The UN's Comtrade database is a good source for commodity-specific bilateral trade data. Users can create their own extracts of data for both value and quantity of trade using different industrial classification codes and download those extracts for later use. Comtrade now also includes data on trade in services. This resource is also available via Databases at Emory.
UNCTAD Foreign Direct Investment Statistics
The United Nations Conference on Trade and Development (UNCTAD) maintains a database on FDI statistics, including flows, stocks, and participation in international investment-related agreements. It covers the years 1970 onward and allows users to download data into Microsoft Excel. UNCTAD's World Investment Reports are another useful source for FDI flows and stocks.