I’m in strong support for this feature. As coincidence wants is, I was just about to ask for a similar feature 😉
On top of just offering a list of classes, it would be a killer feature to use runtime statistics for offering the most likely candidate (based on historical usage) first. For example, in some piece of code of mine, I make heavily use of the Map interface. As everyone knows, Map is implemented by a dozen of classes. Even in just my project there are quite a number of classes implementing it. However, in this particular piece of code, there is (currently) only one single kind of map used.
Implementing this feature however would require a modification of the Java editor, something I don’t think MyEclipse had done before.