iDeaS is an Nintendo DS emulator. It's compatibility rate is growing with each release while it already runs a few commercial games.
Below is a video which demonstrates iDeaS v220.127.116.11 running Super Mario 64. The system used to create this video is an Intel Core 2 Duo E6600 system overclocked to 3 Ghz. The game runs reasonably fast (not great), but there are some graphics glitches. It's likely emulation quality has improved with newer versions however.