• Oral Presentation Advice -
  http://www.cs.wisc.edu/~markhill/conference-talk.html
  Good suggestions for preparing a speech. See especially the "How to Give a Bad Talk" commandments.
• Public Speaking Website - http://wps.ablongman.com/ab_public_speaking_2
  This site contains a great deal of practical information about giving a speech effectively.

Collections of Speeches

• American Rhetoric - http://www.americanrhetoric.com/
  An index and database of more than 5,000 full text, audio and video versions of public speeches etc.
• Douglass: Archives of American Public Address - http://douglassarchives.org/
  An outstanding site from Northwestern University. It is a search engine for online speech and rhetoric sites and may be browsed as well.
• History Channel Speech Collection - http://www.historychannel.com/broadband/home/index.jsp
  Contains brief audio excerpts from over 500 famous American speeches.