Now that Rodot has started shipping official hardware I'm happy to release the emulator I was working on a few months back. This isn't really a proper "release" per se, more like a sneak peek for anyone that wants to see how it's coming along:
https://github.com/Myndale/Simbuino/blob/master/binaries/Simbuino-Install.zip?raw=true
I'll warn you right now, you'll need a fast machine to run it at full speed. I haven't started optimization yet and the entire thing has been developed in .NET and WPF/MVVM...technologies not exactly renowned for high performance! So far I've been concentrating on implementing the features needed by the official Gamebuino library, if you use that then you should be fine but if you start messing around with register settings then things will probably break. The main components that are still missing entirely are SD emulation and bootloader support i.e. you can't call the game loading or page write functions (LOADER.HEX won't run either). HEX files can be loaded from the menu, hit F8 to run them. Screen persistance is disabled by default but you can enable it via the menu to get greyscale support.
I started occasional work on this emulator the same week that Rodot announced the campaign and it's been solely for the purpose of my own personal education, so please don't expect too much. I do plan to continue developing it though, I've found the debugging functions particularly helpful with the graphics optimizations I've been working on this past week.
As always, feedback is greatly welcome. Enjoy!
EDIT: Simbuino is now open source and hosted on GitHub at https://github.com/Myndale/Simbuino, the above download link has been updated to reflect the new location of the compiled installer.