The copyright genie (US only). Librarycopyright.net
Plagiarism Q & A www.indiana.edu/~wts/plagiarism.html
Plagiarism: What it is
and how to recognise and avoid it www.indiana.edu/~wts/pamphlets/plagiarism.shtml
Using evidence www.indiana.edu/~wts/pamphlets/using_evidence.shtml
What is plagiarism? http://hnn.us/article/514