When one types name of the new class (not being imported yes in the current class) - pressing Alt+Enter displays a small pop-up window with all possible options. Now - many of them make absolutely no sense for me, ever :) Like "sun.misc.Queue" when I type "Queue" thinking of "java.util.Queue" (http://img441.imageshack.us/img441/7506/65129399up0.png) and "java.awt.List" when I type "List" thinking of "java.util.List" (http://img261.imageshack.us/img261/1665/99818914yj9.png).
If there was a way to configure IDEA to never "suggest" packages like "sun.", "java.awt.", and "com.sun.*" - then in many more cases "Add unambiguous imports on the fly" would pick up the right choice automatically ! This would make developer's work much easier as it won't have to answer the same question (what "List" do you mean?) again and again.
Something similar to "Settings | Debugger | Do not step into the classes"