Nes Games?

The ROMS are the digital copies of the games for an emulated system.
Also, you may need the BIOS from the system you want to emulate, unless they are included in the emulator.

You want legal ROMS, or commercial games? Commercial game ROMS can be downloaded many places online, google it (many torrent sites), just remember that it is illegal to have a ROM of a game you do not own the physical cartridge for more than a 24 hour "evaluation period."

There are also free games things that people may have developed for the nes over time, a google search should bring these up also.

 

Also, to get them on to the iPod, you need to use SSH.

 

That is not correct at all, at least not in the US.

1. While US Copyright Law Section 117 does allow you to make backups of your media, the law clearly states that the owner must make the copy or authorize someone else to make the owner a copy of the owner's media. But US law prohibits the use and ownership of devices and software that create game ROMs. So while you can legally own a ROM you created, you cannot legally make one because you cannot legally own anything that helps create a ROM. Basically, this all sums up to the fact that ROMs are illegal in the US, even if it is in a round-about way.

2. In Atari v. JS&A, the US District Court said games ROMs are not covered by US Copyright Law Section 117. This is because S117 is to protect the owner against deletion, corruption, etc. The court ruled that video games are not easily erased, so they are not covered. It went on to say that games ROMs are illegal even if the owner makes the copy himself.

And by the way, that rumor about a 24-hours evaluation period is complete BS. Someone just made that up to feel better about their own piracy.

All this goes right out the window if the copyright holder allows users to copy the game, which happens but is still fairly rare.

 

Now that's a definitive answer
But back on topic, this has been discussed countless time and due to it's shady nature, you're not likely to find any better information than already mentioned here, Google may be able to help you out.