Awesome
GBOxide 
A GameBoy Emulator written in Rust
Download 
Launch Instructions
Run from the command line with a ROM file, like so:
$ ./gboxide roms/game.gb
Controls
- DPad: Arrow Keys
- A: x
- B: z
- Start: Return
- Select: Space
References
Most of these are linked from avivace/awesome-gbdev, but these are the resources I've found most useful.
- Pan Docs - GbdevWiki
- Gameboy (LR35902) OPCODES
- GameBoy CPU Manual
- GameBoy Crib Sheet
- Cycle-Accurate Game Boy Docs
- Official GameBoy Programming Manual (less relevant for emulation but still a handy resource)