Basilisk II, a 68K Mac emulator running on the Raspberry Pi. Everyone asks if the Pi can do this or that. The only trick here was building from source (it's not in the Raspbian repos) which was easy:
# apt-get install git libsdl1.2-dev
# git clone github.com/cebix/macemu
# cd macemu/BasiliskII/src/Unix
# ./configure --enable-sdl-video --enable-sdl-audio --disable-vosf --disable-jit-compiler
# make install
There is no 68000 JIT for ARM CPUs yet so it's not lightning-fast but is eminently usable. As ever, it runs faster on the console (as shown here) without the bloat of Xorg. 8-bit color mode crashed but all the other modes including 16-bit color works fine. Audio lags by around or perhaps a little more than 500ms.