The Yearbook of Experts, Authorities and Spokespersons - Great to locate authorities on topics of interest.
Biography - 25,000 Bio's of personalities.
History Channel - If its a historical speech you might get some info here.
Humour - Can always add some to make it enjoyable.
Executive Speaker Newsletter - "A goldmine of inspirational tidbits to spice up a talk"
Internet Public Library - Great for basic research
FedWorld Information Network - 480,000 US Gov't Reports
The above links were published by William Hennefrund in the January 2002 edition of "The Toastmaster".
Bartleby - Best Literary Resouce for 2002. Good reference section, daily Biography, word, quote and poem and sells books.