As there was some positive feedback to the idea of creating our own compiler, I have gone ahead and started a new project on Github and created an initial design document on how I think it might work. I've taken the liberty of giving it the code name "Goshawk." If you are curious as to why, google for details on animals that predate upon falcons ;)
You can take a read up on my ideas so far at https://github.com/DavidArno/Goshawk/blob/master/documents/Goshawk compiler initial ideas.pdf?raw=true (shortform: http://is.gd/94rcIb) the project is https://github.com/DavidArno/Goshawk should you feel the urge to fork it and help out. Obviously, as per the mentors' request recently, whilst it makes sense to experiment with this compiler on Github, we need to keep discussions happening here. Perhaps we could prefix topics with [Goshawk]? That way those that wish to concentrate on making the framework better, rather than upon side projects like this, can filter out our discussions. For anyone wanting to get involved, but is unsure where to start, you could do worse than head over to http://www.antlr.org/ and get reading :) David.