This Nation
This nation.com: What Is a Filibuster?
This site answers the questions "What is a filibuster? Why are they permitted in the Senate but not the House? Can you do anything to stop one?" Good discussion of the term in the context of U.S. government.
BBC
Bbc News: Filibustering
Gives a brief explanation of the technique in the context of parliament procedure. Also provides an example of a time it happened in the British Parlament.