The MMC1 isn't too bad unless it's the MMC1A, then you have to have a reset routine in every bank. Something that's not really documented anywhere that I know of.

Hyde's idea sounds good, some reusable programming examples would be good to have. For a startup routine, I've got this 'nes_init' macro that I use in here:
http://www.parodius.com/~memblers/nes/macros.s

But the NMI handler is where the really important stuff goes on, and what needs to be done varies a lot on the program. A template for it would be useful.

That's what we need in the Wiki somewhere, a "how to successfully program the NES" section.