Intel x86 Opcode Reference?

Question

What is a relatively quick and easy method of looking up what an arbitrary opcode means (say, 0xC8) in x86?

The Intel Software Developer\'s manual

Answer 1

Here is a pretty nice visual. Doesn't go into much detail, but if you just need to look up a hex value really quick, this should do it-

Source: http://pnx.tf/files/x86_opcode_structure_and_instruction_overview.png