Legal dictionary
http://dictionary.reference.com/legal/ (legal dictionary)
US law
http://www.findlaw.com (US law)
http://library.findlaw.com (Articles about US law)
http://www.law.cornell.edu/ (US law)
http://www.law.cornell.edu/search/index.html (US law)
EU law
http://eur-lex.europa.eu/en/droit_communautaire/droit_communautaire.htm (comprehensive introduction)
http://europa.eu.int/eur-lex/en/search/search_case.html (EU case law)
http://europa.eu.int/eur-lex/en/index.html (EU primary sources)
http://europa.eu.int/eur-lex/lex/RECH_legislation.do?ihmlang=en (EU search engine)
International law
http://www.jus.uio.no/lm/private.international.commercial.law/
(National + International law)
(CISG includes notes and case law relating to the CISG)
WTO
http://www.wto.org/english/tratop_e/tratop_e.htm (WTO trade topics)
http://docsonline.wto.org/gen_home.asp?language=1&_=1 (WTO documents)
http://www.wto.org/english/tratop_e/dispu_e/dispu_e.htm (WTO dispute settlement gateway)
UNCITRAL
http://www.uncitral.org/uncitral/en/uncitral_texts.html (UNCITRAL texts)
http://www.lexmercatoria.net (Links to various legal topics relevant to international trade)
http://www.worldlii.org/ (Case law from different jurisdictions)
General resources for research on the internet
http://www.un.org/en/development/index.shtml
(UN website gives contextual information not only about the workings of the UN but also about thematic areas including population, social development, governance, global stats and international trade)
https://www.cia.gov/library/publications/the-world-factbook/
(CIA factbooks)
(Globalis is an interactive world atlas)