If you are searching plugin for Struts 2 then I give you advise that manually configuration of Struts 2 is too easy and it is good to use it own.
Once I have use Plug in for my application in Struts 2. Have a look for more details
Struts 2 Eclipse plug-in. But I think using this too tough for me to develop Struts 2 application. So it is better to use manually Struts 2 configuration. Struts 2 have easy to configure no need to do much.
And for Struts 1.3 Myeclipse provide inbuilt functionality for configuration.