Important Legal Documents: Constitutions
US Constitution
http://avalon.law.yale.edu/18th_century/usconst.asp
The US Constitution and its amendments. This website also contains many more important legal documents of the US.
Canadian Constitution Act of 1982
http://www.solon.org/Constitutions/Canada/English/ca_1982.html
The Canadian Constitution Act of 1982, which fully ended British rule and established the modern constitution.
EU Countries' Constitutions
http://www.constitution.eu/
The constitutions of EU member states. Also contains links to the Treaty of Lisbon, and more.
Australian Constitution
http://www.aph.gov.au/About_Parliament/Senate/Powers_practice_n_procedures/Constitution
The constitution of Australia, as well as a link to a complete .pdf file.
Russian Constitution
http://www.constitution.ru/en/10003000-01.htm (translations)
http://www.gov.ru/main/konst/konst0.html (original Russian)
The constitution of Russia, adopted in 1993 following the collapse of the Soviet Union.
This list is still being updated.