Microsoft has posted the online documentation for the KMS keys for their latest OSes.
In my case the only KMS Setup Key’s I care about are below:

Windows Server 2012 Datacenter: 48HP8-DN98B-MYWDG-T2DCC-8W83P
Windows 8 Enterprise: 32JNW-9KQ84-P47T8-D8GGY-CWCK7
Windows 8 Professional: NG4HW-VH26C-733KW-K6F98-J8CK4