It is a great idea for an app, however a emulator has been asked to be ported once before. Virtual Jaguar. Only one problem with that emulator however. Lot of incompatibilities with games, it's kinda slow, and needs more optimisations. In other words it needs a lot of work, and stabilizing before anyone would consider porting it. Otherwise it would just end up being a huge headache for the person porting it.
I wish I knew more than just BASIC programming. If I knew some C/C++ I would love to help develop this. I hope someone with more programming knowledge than me feels the same.