Allow generic primitive types
This is simple to understand, but probably hard to implement. Allow passing of primitive types to generic declarations. There are many useful places for this, one example is anyware where seperate methods have to be created for each number primitive type.
For example, java.util.Arrays would drop most of its weight. Collections API would not need autoboxing. Imagine the simplifcation of java.awt.geom or java.lang.Math.