yUML Test On GitHub
yUML is a simple tool for embedding UML diagrams in wikis and blogs without needing any UML or diagramming tools.
Here's an idea of how it could be used in your repository readme.markdown or wiki.
View the RAW source to see how images are made.
Git users may own repositories.
The may also be collaborators.
Each repositories have a Git repository, a ticketing system and a price plan.