Nintendo Game Boy Emulator in C# using SlimDX, written in 2011 by xdaniel

Downloads: SharpBoy v0.1 (32-bit binary)

Default controls:
B: A
A: S
Start: Return
Select: Space
D-Pad: Cursor keys

Notes and bugs:
Emulation is still incomplete and has bugs, especially with GBC games
No sound, serial link, SGB, etc. for now
No documentation yet either; controls cannot be changed from within the program (edit config.xml manually after first run)
GUI has some quirks (ex. window resizing), FPS limit and counter aren´t accurate
Debugger slows down emulation speed considerably, needs some serious optimization
Probably more...
...and despite this, there´s a bunch of playable games: