Continuity is a drawing and a modeling tool at the same time and tries to combine the best of both worlds to help you create beautiful formal models
Check (and contribute to) the OCL repository in GitHub
My twitter list with the official accounts of UML, modeling and model-driven tools I know
We have embarked on a project to find (and/or define) good use cases for teaching several flavours of model-driven /model-based engineering. Do you want to join us?
First empirical study on the adoption of Eclipse-based modelling technologies in open-source projects on GitHub. Promising results!