
Rubrics improve efficiency and reliability in grading by specifying in advance what is necessary for each grade level. See http://jonathan.mueller.faculty.noctrl.edu/toolbox/rubrics.htm for more information. Examples of the two types:
Rubistar (http://rubistar.4teachers.org/index.php) guides you through making your own. Registration is required for some access.
Another good resource that discusses how to make your own is: http://pareonline.net/getvn.asp?v=7&n=25
Book references on rubrics and classroom assessment