This is a plugin for Eclipse that turns it into a Maya IDE. As it is Python-centric, it also requires the pyDev plugin. Features include:

 - Send the entire contents of an editor to Maya

 - Send a highlighted selection to Maya

 - Python and mel scripts supported

 - Anything done within Maya's own script editor is also echoed in the console view

 - Change the port number of the socket at any time

 - Open up documentation for Maya's Python API, Python Commands,
Pymel, Qt, PySide, PyQt and User options

 - Get results back from Maya in it's own console view 

 - Eclipse Helios, Eclipse Indigo and Eclipse Juno supported. Requires PyDev plugin.

For more info, see tutorial here:
 http://www.creativecrash.com/maya/tutorials/using-tools-scripts/c/using-eclipse-as-a-maya-ide