well, judging by your tone, it doesn't sound like you've got the intention of doing more than the preliminary work (and aren't already familiar with coding such a thing as an emulator) -- but hey, I don't know who the heck you are, maybe you can whip things like that out without batting an eyelash! At any rate, as a general response..
I think the most popular/respected/well received emulator programs out there are those that provide nostalgic value, in that people can enjoy the same games that they did generations ago (before all the 3D hooyah kicked in.. in some cases, before actual discernable GRAPHICS kicked in!) With that in mind, I'm all for emulation of an older, classic system like (as you listed) the 2600. Sure it's dated as hell, but when we were kids we all would have LOVED such a thing as a portabe device to play all those games with. Likewise with, say, a colecovision, etc. And a little later, something like the atari Lynx - while okay, it is sorta redundant to emulate such a device on another portable system, I agree. he original can be had for a low price, likewise with the games, right now. But I have one and though it is still enjoyable, it's pretty bulky and cumbersome to whip that thing out and struggle to get it to work still (huge power consumption as well..) Yeah, it would be nifty to have a lynx emu, I admit (though surely more limited then the other systems mentioned)
I am kind of against the idea of emulating systems that are available NOW, or in the near future (the nokia n-gage thing). Okay, it is pretty cool that someone can do that, it is a novelty. When N64 emulation (on the PC) hit the scene it was a shock, and it was just ridiculous that someone had a working GBA emulator (again, on the PC) before you could even BUY the system. Yes it's a novelty, but on some level it hurts those systems and does a little damage to the scene. I agree that it is still technically impressive (and won't be a hypocrite, I have taken advantage of the same technology!) - but given the chance, I'd say it is more moral/interesting to emulate a system that's just.. no longer available! "Use your powers of programming for good, not evil!!"
Anyway, the bottom line is that even if you don't plan to get very far with your work - WHATEVER system you decide to concentrate on - just about any work you do could only be beneficial to the scene, and inspire others to a little healthy competition. (go on, there doesn't have to be just ONE SNES emulator or megadrive/genesis emulator, just like in the PC scene - there's a reason why people work on them from different angles!)
Good luck, aspiring emu authors..
