in my opinion, for the consumer space (no particular order)
Intel E6300 - the first Conroe, the CPU that shocked the world.
Intel i486DX2 - 66MHz - reigned for years until the introduction of the Pentium processor.
AMD Athlon X2 3800+
Intel i7-920 - the second revolution
Intel Q6600 - the beginning of the mainstream quad-core era for consumers.
Intel E6300 - the first Conroe, the CPU that shocked the world.
Intel i486DX2 - 66MHz - reigned for years until the introduction of the Pentium processor.
AMD Athlon X2 3800+
Intel i7-920 - the second revolution
Intel Q6600 - the beginning of the mainstream quad-core era for consumers.