* PPC - PowerPC (Motorola) and POWER (IBM) -- I know there's a "common"
  instruction set that works both on the "consumer" PPCs and the HPC
  (high performance computing) POWER chips.

* MIPS - I know a little bit more about these, but I *suspect there's
  a simple common instruction set

* HPPA - I know very little about these, is there a common instruction set?

* IA64 - reports of the IA64 instruction set tell that it combines
  the "elegance" of the IA32 CISCy instruction set with
  the "elegance" of the HPPA RISCy instruction set... :-)

I intend to do nothing on these except raise gui^H^H^Hawareness :-)

--
$jhi++; # http://www.iki.fi/jhi/
        # There is this special biologist word we use for 'stable'.
        # It is 'dead'. -- Jack Cohen