Cumin is a good substitute for ground coriander because it provides a bright flavor that is similar to what you expect from coriander. Cumin and coriander are both used regularly in Latin cooking, and many culinary experts find that both flavors mesh well with the flavors of Latin food. Some experienced chefs also find that fennel seeds or caraway seeds can replace ground coriander if you prefer the seasoning to have more texture than a ground spice.
Coriander is actually the name of the seed that grows into cilantro. For this reason, chopped fresh cilantro leaves also make an ideal substitute when the dish benefits from a bit of color and texture.