I recently started using a feature in Eclipse 3.6.1 that I didn't notice before: the "Save Actions".
Basically you can configure some actions that will be done automatically when you save a Java source. Some of them are really useful, like Organizing the imports, adding 'final' to private member instances, etc. Here the screen-shot of it, with my preferences:
From now on, nomore unused imports and better immutable classes.