Every now and again, I make use of the Eclipse refactoring feature. Some techniques are more obvious then others and some I never tried.
What refactoring is most useful for you and why?
Note: I find this presentation very useful, perhaps because it is example driven therefore easy to understand:
"Refactoring for everyone - How and why to use Eclipse's automated refactoring features"
Edit: This article is useful as well (Thanks jitter)