Docotopus is a script applied to a Google Spreadsheet that allows a teacher to share and collect Google Document (Docs, Spreadsheets, Slides, etc.) assignments with his or her students.  Below is a Google Hangout video conference between Jerry Williamson and Patrick Bryan explaining Doctopus and the details for using it (view the Hangout page here).  Below the video is how-to document for Doctopus (by Christy Fennewald).