Well there is AimgaOne and Pegasos. AmigaOne, the one that runs OS4, is currently unavailable. It´s also of
very expensive and of dubious quality, it has DMA-issues etc( Before somebody starts to :flame: sure you can patch and work around it but its still there).
Pegasos is another PPC-machine with more modern hardware. It seems that they are mainly focused at running opensource OSes at the moment but it also runs MorphOS a OS thats compatible with the previous versions of AmigaOS.
For red and blue tinted views of the world look at
http://www.amigaworld.net/ and
http://www.morphzone.org.
If you can stand x86 :-D then there is always
http://www.aros.org/.
See also
http://www.aros-exec.org/Why not try a AROS live-cd. It will work on your regular machine. Great for trying it out.
Edit: I assume you already know about WinUAE/AmigaForever?