A new version of RxNES has been released, with speed increases and constant improvements and features.

RxNES is a nes emulator based on mynes, it uses the unity engine, which allows graphic mods, 2D and 3D, as well as sound and music mods.
Its still very much wip, but includes a sample mod for super mario bros::

RxNES v3.039

news via http://www.emulation64.com/view/2925/RxNESv3039/