Rubrics are scoring tools that explicitly represent performance expectations for an assignment based on specific elements. A rubric divides the assigned work into highlighted characteristics and provides clear descriptions of work associated with each characteristic at varying levels of mastery.
TeAchnology; Rubrics, Rubric Makers: links to all sorts of rubric makers for a variety of subject areas and assessment forms in K-12 environment, to printable rubric collections for all sorts of purposes, and to rubrics resources (All About Rubrics); although this is designed for K-12 teachers, much of it is applicable
Carnegie Mellon; Grading and Performance Rubrics: rationale for using rubrics and good examples from a variety of disciplines and assessment forms; higher ed specific
Rubistar: free tool to help you create rubrics for a variety of projects