Rubric Generators are easy to use and they allow you to quickly set up student-friendly rubrics that you can use in your courses. Here are some free tools that you will find helpful in your development of rubrics for your courses.
Rubistar: A free tool for teachers who wish to create rubrics with ease. This is sponsored/created by 4Teachers.org, which has other tools as well.
Rubric Template: This is not as adaptable as the first one, but it does cover the basic levels and would be easily adaptable.
The Rubric Machine: Another free rubric generator, this one by Landmarks for Schools.
Online Assessment Resources for Teachers: Read all about authentic assessment here (this is a list of links to articles about rubrics, portfolio assessment, etc). This page is from University of Wisconsin-Stout.
Discovery School.Com: While this is geared for K-12, there are many resources here that will be useful for teachers of any level, including a long list of rubric samples.
What follows are some examples of rubrics used to grade essays and also to determine letter grades. I've compiled rubrics here that are in line with my own teaching philosophy and understanding of the traditional meaning of letter grades--an essay that meets the bare minimums, for instance would be a "C"-level essay, while one that does not meet those requirements would be a lower than satisfactory grade. To achieve an "A", a paper must be "fresh" and free of serious errors. It should go beyond the minimum expectations of the assignment.
Rubrics for Essays and Longer Assignments
Composition I Rubric: From Auburn University, this rubric is used in their first Composition course.
Composition II Rubric: Auburn University
What Essay Grades Mean: From Auburn University, this rubric is used in their World Literature courses (formerly "Great Books"), which is a sophomore level literature survey course required of all students
Rubrics for Discussions
Landmark's Discussion Rubric
Discussion Rubric: California Virtual Campus