online UML diagram tools and MySQl table online designer

Online UML diagram tools
1)ArgoUML is not only a free UML modelling tool, it is also an Open Source Development project . You can launch via java web start or download it.
http://argouml.tigris.org/
 ArgoUML with relational database modeling
http://argouml-db.tigris.org/
2) Another is  genmymodel
http://genmymodel.com
You can login with Github account.

3) MySQL table and schema  online designer:
http://diagrams.seaquail.net 

List of Unified Modeling Language tools
 http://en.wikipedia.org/wiki/UML_tools