Plagiarism.com
the online resource for people concerned with the growing problem of internet plagiarism. This site is designed to provide the latest information on online plagiarism and explain how Turnitin and iThenticate are now being used by educators and content creators all over the world to fight plagiarism and restore integrity to written work.

Plagiarized.com
The purpose of this site is to help instructors and parents better understand how the internet can facilitate plagiarism. We present strategies to prevent plagiarism, explain some of the underlying causes, and provide advice on dealing with cases of confirmed plagiarism.

Community Learning Network:Plagiarism Theme Page
Students and teachers will find curricular resources (information, content...) and reference materials to help them learn about this topic. In addition, there are also links to instructional materials (lesson plans) which will help teachers provide instruction in this theme.

Glatt Plagiarism Services
The website claims to deter plagiarism and encourage academic honesty in the production of three different software programs, which are the Glatt Plagiarism Teaching Program (GPTeach), the Glatt Plagiarism Screening Program (GPSP), and the Glatt Plagiarism Self-Detection Program (GPSD).

The council of Writing Program Administrator
Defining and Avoiding Plagiarism: The WPA Statement on Best Practices. This statement responds to the growing educational concerns about plagiarism in four ways: by defining plagiarism; by suggesting some of the causes of plagiarism; by proposing a set of responsibilities (for students, teachers, and administrators) to address the problem of plagiarism; and by recommending a set of practices for teaching and learning that can significantly reduce the likelihood of plagiarism.

The Owl at the Purdue: Avoiding Plagiarism
This resource offers advice on how to avoid plagiarism in your work. It defines debatable activity in terms of plagiarism.

Wikipedia

Plagiarism Today
a site about plagiarism, content theft, and copyright issues online