1. Game of life simulating itself 2. Lisp interpreter (in C? or in Lisp) 3. a game engine?? 4. Bitcoin 5. Other distributed systems?? (Spanner?) 6. AI/deep learning representative. GPT4? AlphaGo? Pikadditions? 7. ?

- Error correcting codes (viterbi, reed/Solomon, ...)

- cryptography in general

- data compression

- a lot of DSP stuff is pretty magical in it's various applications - digital filtering, modulation/demodulation, recovery of weak signals in noisy environments, beam-forming etc

There's a lot of really amazing, largely mathematical, foundation work that we now tend to take for granted and without which we'd be back in the relative dark ages.