Having just finished a geometric group theory course I was hoping to see something about the word problem for automatic groups, or at least an algorithm to compute Dehn presentations of f.g. hyperbolic groups, but it looks like a cool resource with plenty of interesting topics.
Another book the HN crowd might like is Shoup's "a computational introduction to number theory and algebra"[0], it is much more broad and with litte focus on implementations, but a very interesting book nonetheless