Hi maxxx, I am pretty sure I did make an 8 core version of RealTemp once upon a time but the guy I wrote it for said it was too big and ugly so I scrapped it. Unfortunately I don't have enough time or hardware for an 8 core update now.
Lately I have been working on a special edition of RealTemp for my friends over at Tech|Inferno which is just about done.
http://img210.imageshack.us/img210/2225/realtempti.png
It includes the return of VID and VID based power consumption monitoring for Intel's 3rd Generation Core i CPUs.
I also added a column to report the CPU Package temperature but in my testing, that just looks like the maximum of the 4 cores so that is not too useful.
There is also a new C-State reporting window. I like using C3/C6 to save some power but most enthusiasts at XS turn that junk off when overclocking.
WaterFlex: I don't know of any easy way to read CPU registers in OS X. In Windows I am using the WinRing0 library but I don't know of anything equivalent for Mac. I also don't own a Mac or any sort of development tools so you're out of luck unless you are running Boot Camp.