Getting Emulators (PSP,DS and more) on your non-jailbroken iOS device - Play your favourite retro games on your iPad/iPhone with minimal effort! - Wololo.net
Here's how to install Nintendo 64 Emulator & play N64 games on iPhone – works with the latest iOS | N64 Emulator for iOS - JILAXZONE
This app lets you play N64, PS1 and GBA games on your iPhone without a jailbreak