I recently found a fun linear-time systolic sorting algorithm. I'd describe the serial implementation as unconventionally obvious. It's like insertion sort, without all the bother of swapping.

  def index_sort(a):
    n = len(a)
    output = [None] * n
    for i in range(n): #can run in parallel, damn the GIL
      index = 0
      for j in range(n):
        if a[j] < a[i]:
          index += 1
        elif a[j] == a[i] and j < i:
          index += 1
      output[index] = a[i]
    return output