Hot off the press. As in I just learned about this resources on a phone call with a teacher two minutes ago. It is a rubrics library that can be (1) a source of assessment ideas, and (2) a repository to create and store your own editable rubrics.
What I love about these rubrics is the attention given to measuring more complex skills such as creativity, problem-solving, and critical thinking. The site takes a few minutes to load but once the chest is open many assessment treasures are at your fingertips.