One app that manages your citations, bibliography and even checks for plagiarism.
Slate: A plagiarism checker under your mouse cursor.
Drag the text you want to check for plagiarism click the S button to check it for plagiarism in real-time. The plagiarism checker compares your selected text with journal articles, news papers and 8 billion webpages in an instant.
The popup includes the URL of the page which matches your text at the bottom, and clicking on the link will take you to the web page on your browser.