I love the idea of bare-metal ports to the Pi. I saw snakeware posted here not too long ago. Are there other examples? ColorForth would be interesting as well
In addition to the Interim Lisp system I mentioned in another comment, there are a number of bare-metal applications for the Raspberry on github (mostly ports of games).
I especially like this Commodore 64 emulator (also based on circle): https://github.com/randyrossi/bmc64