The Implementors plugins add the possibility to jump to the implementation of of an interface. Alternatively, you can jump to the interface of an implementation.
The jumping to implementation/interface works for plain Java files. In addition, when associating EJB deployment descriptors with a project, the plugin is made aware of the connection between the EJB interfaces and the implementation class, something which is not specified in the implementation class itself.
Latest version for Eclipse 2.1.x or Eclipse 3.0.x: v0.0.14
Latest version for Eclipse 3.1.x: v0.0.15
Latest version for Eclipse 3.2+: v0.0.16