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
First empirical study on the adoption of Eclipse-based modelling technologies in open-source projects on GitHub. Promising results!
Contribute to our glossary of software modeling / model-driven terms . You can do it through the github repostory created to support this effort.
My proposal of a virtual federation of existing model repositories as the best way to finally have a useful set of modeling artefacts for the research community