Here is an example of two rabbits that are getting along very well. Houserabbit society has a lot of really great information on how to bond two bunnies, this video clip shows the result of a successful bonding session. If you are introducing your rabbit to a new friend and one bows its head to the other, this is called "presenting." What the rabbit is saying by bowing its head in such a way is that it would like to be groomed. When the request is met with licking on the forhead, you can consider the two rabbits a good match, barring any other negative behaviors.