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.
iCivics
I Civics: Mini Lesson: Filibusters
Students learn about filibusters and how and why senators use them, then they take a look at how news coverage of a filibuster can be transformed through neutral, positive, or negative framing.
Social Studies for Kids
Social Studies for Kids: The Filibuster
A filibuster is a simple parliamentary procedure used in the Senate to prevent a measure from being brought to a vote usually when one or more senators attempt to delay or block a vote on a bill by extending debate on the measure.
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.