The x86 family is, unsurprisingly, the messiest.
- x86 is the most generic tag, and the most widely used.
- There are tags for x86 subfamilies: 8086, i386, ia32, pentium. In practice, x86, i386, ia32 and pentium seem to be used mostly interchangeably. 8086 looks more specific to 8086. What should we do?
- Merge i386, ia32 and pentium into x86?
- Do a clean-up effort and reserve i386 for issues specific to i386 (or to i386 and i486?), reserve ia-32 for issues specific to i386 and above, and use x86 for generation-independent questions only? What about questions specific to more recent x86 generations (when they're not sse or sse2)?
- A variant of the above, where ia-32 and i386 are synonyms?
- Other proposals?
Strangely, I found nothing wrong around ARM families. (Note: ARM7 and ARMv7 are not the same thing.)
“Exotic” CPU families
ppc is used for both powerpc and pay-per-click. This looks like a simple disambiguation job (and some of the pay-per-click questions might be better off on Webmasters, but I don't know if there are any still there that should be migrated).