IEEE Spectrum has an article titled "25 Microchips That Shook the World" . Their choices include
chips like NE555, TMC0281, 6502, TMS32010, PIC16C84, μA741, ICL8038, WD1402A, ARM1, KAF-1300,
IBM Deep Blue 2 Chess Chip, Intel 8088, Micronas MAS3507 MP3 decoder, Mostek MK4096 4K DRAM,
Xilinx XC2064, Zilog Z80, Sun SPARC, Tripath TA2020, Motorola MC68000,  C&T AT Chip. My personal
favorites are 555, 741, Z80 and ARM1. I had great time reading the artilcle,  brings back lots of good
memories.