EMU][, which was formerly called Dapple ][, aims to emulate the various models of 8-bit Apple ][ computer as accurately as possible. In addition, we are working on a potential solution which would allow the use of EMU][ without the need for Apple ROM code.
There is still a lot of work to be done for EMU][. The latest release as I write this is 0.31; perhaps a newer version will be made available soon. (I just released a binary 2003.0704)
Dapple/EMU][ Download Pages