Fwirt has released a total of 6 Virtual Boy demos which function as example code as well as base code to start your own projects.
Quote:
This folder contains a bunch of demos that I wrote at the beginning of the summer to help me relearn (and expand my knowledge of) Virtual Boy programming. I'm releasing them in the hopes that they will be helpful to someone else. They are aimed at people who already know how to program in C, but want some code examples for Virtual Boy to supplement the programmer's manuals. They are released under a modified BSD license (so basically do what you want with them but don't blame me...) Share and Enjoy! -Fwirt