(A500, A600, etc...) Although the name varies, this emulator exists for Windows, Macintosh, RISC OS, Linux, Unix and other systems, including the Amiga itself.
It is capable of emulating a 68K Amiga, including undocumented behavior, with OCS and/or AGA chipsets and modern graphics and audio subsystems, including true colour graphic libraries and Amiga AHI 16 bit audio subsystem.
However, a copy of a Kickstart ROM from a real Amiga is required for legal use, which is still protected under copyright laws.
The Amiga Forever[2] emulation package offers legal copies of Kickstart, Workbench and various games.
Another legal option for Amiga emulation is the AROS Research Operating System, which is available as free software.