Amendments

Government Printing Office Supreme Court Cases
http://www.access.gpo.gov/su_docs/supcrt/index.html
Type in an amendment to search for summaries of relevant Supreme Court cases.

Landmark Supreme Court Cases Supreme Court Cases
http://www.landmarkcases.org/

Facts.com Primary Source Documents 
http://www.2facts.com/stories/mainmenu.asp
Click on Historic  Documents on the lower right side of the screen to take you to Primary Source Documents arranged by title. Click on U.S. Constitution: Amendments XI-XXVII (11 - 26) to get text of the amendments or scroll down for links to related articles.

 The Avalon Project at Yale University.
http://www.yale.edu/lawweb/avalon/chrono.htm
Documents from 1492 – 1988.