The Mylar plugin for Eclipse (available for versions 3.1 and 3.2M3 only) is, without doubt, one of the most innovative ways to change out interaction with IDEs.

Let's see a typical example of our daily work on Java project. You get a task, which can be an enhancement, new feature or bug fix. Typically, you have your project as a tree on the left-hand side, along with the list of all methods / fields (either as sub-branches of the project tree or as a separate tree). When you need to view or change source code, you either locate the corresponding entry in the project tree, or use one of the many shortcuts (such as Ctrl+Shift+T in Eclipse) to locate that class. Typically, you will need to access a number of classes, with a couple of methods in each one of them. Now, consider what happens in an existing project.

You have hundreds (if not thousands) of classes in tens of packages, each class having quite a few functions (depending on the previous team members, it can get to hundreds). The classes that you need to change for a particular bug fix are most likely under different packages. When you need to go back and forth between these classes, you waste valuable time (and energy) to do so. Wouldn't it be nice to have a context view of your workspace. This view would contain only relevant branches of the project tree, the classes you are working on and the methods that you are changing. Ideally, the IDE itself would track the changes you are making to the codebase, continually updating the context view. Mylar plugin for Eclipse does exactly that.

Here are few screenshots that show the differences (before and after applying Mylar):