Create an open source javac for experimenting with new features
There are some terrific ideas being brought up, more than a few I wish I could try on for size and see how they work out.
Towards this end how about if Sun release an open source version of javac, to allow developers to implement their ideas without having to build a compiler from scratch? It seemed like they did something like this for generics.
We could setup a project page for it, to support the experimenting with new language features, to help developers who think they've got a great idea on how to actually implement that within the compiler.
If there is already an open source Java compiler written in Java, point me to it. If there isn't ... why not?