In the upcoming IntelliJ IDEA 10.5 some new Groovy refactorings will appear.
The first of them is Introduce Parameter. It allows you to select any expression inside a method and make from it a new method parameter. All the usages of the method in both Groovy and Java will be auto-updated.
The second one is Introduce Field which provides you with an ability to quickly create a new field from any expression inside a class.
No doubt these 2 introduce refactorings will be a good addition to the existing Introduce Constant and Introduce Variable. You are using them, right?