XOR lists are obscure and cursed but cool. And not useful on modern hardware as the CPU can't predict access patterns. They date from a time when every byte of memory counted and CPUs didn't have pipelines.

(In general, all linked lists or trees are terrible for performance on modern CPUs. Prefer vectors or btrees with large fanout factors. There are some niche use cases still for linked lists in for example kernels, but unless you know exactly what you are doing you shouldn't use linked data structures.)

EDIT: Fixed spelling