And also the SMS/GG emus - SMS32 and fSMS (the former doesn't have savestates, but is compatible in a couple of places where the latte risn't).
And Wonderswan, of course, although the only emu we've got for that is a titchy corner-based resolution emu, and not amazingly full speed. But better GFX than the nes.
A few (not many) GBC games are too - have a look at fGB32 if you'rew interested. But considering a GBC processor is almost identical to a NES iirc, there's not a massive difference there...