NES.app is a Nintendo emulator for Apple’s iPhone. NES.app uses a modified version of the popular InfoNES emulation core to mimic the 6502 processor in a Nintendo Entertainment System, allowing you to play ROM dumps of games designed for the NES console. ROM dumps are files containing the dumped instruction code from a physical cartridge. In many cases, you are legally entitled to posess a ROM dump of any game that you presently own. ROM images for NES are widely available online, or with the appropriate hardware, you can dump them yourself directly from the cartridge.

NES.app started as a fork of iPhoneNES v0.01, but has been completely rewritten to run very fast, and with many additional features including full sound, game genie codes, saved games, battery-saved ram support, and full screen support.

Changes since NES.app v0.99.02:

[nervegas] Changed Speaker/Headet/Mute button to use colored indicators. [nervegas] Tapping status bar now reloads lists + scrolls to top
[nervegas] Added fourth game genie code slot; sped up game genie a bit
[nervegas] Screen flip to affect on emulation view, not browser
[nervegas] Removed taskbar in landscape mode
[nervegas] Enlarged full-screen mode A/B buttons for landscape view
[nervegas] Enlarged full-screen mode directional pad for landscape view

http://iphone.natetrue.com/nesapp/