Antlr Plugin – Generates parsers that you can use in your code from a very concise domain-specific language.
QueryDSL Plugin – Interrogates your database and creates data access objects that you can use to write SQL- like queries in your Java code.
Test Report Plugins – Make cool report websites that show you how well your unit tests are covering your code.
Shade Plugin – Allow you to bundle all of your classes into an uber-Jar that is runnable. This way you can deploy just one artifact. Also, can change packages of your dependencies to work around conflicts.