Depends upon the purpose of your original question. Were you asking about on-chip buses used to connect processors and memories? If so, there are even simpler on-chip buses than Wishbone & AMBA. And of course things like USB, CAN, PCI, VESA are all widely used buses in computers, but not generally for communication between things on the same chip.
Wishbone is open source, easy to understand and is used by many designs in the OpenCores project, but it is almost unknown in commercial applications. IBM use CoreConnect, a few companies use OCP from Sonics Inc, but in my experience AMBA is the most widely used.
I posted an introduction to AHB, one part of the AMBA specification here:
**broken link removed**