The Computer Language Benchmarks Game is a collection of 429 programs, consisting of 13 benchmark reimplemented across 33 programming languages. It is a fantastic resource if you are trying to compare programming languages quantitatively. Which, oddly, very few people seems to be interested in doing.
I’m really typecasting myself here. If there were an international “Person most likely to write a Spectrum emulator in Javascript” award, I’d have taken it for the last five years running. So here it is - probably the most stereotypical project I’ll ever come up with.