Anders -
I am probably not the best Buddhist to deal with your question. The tradition/school I practice doesn't view "nirvana" or stepping off the wheel of rebirth as a goal. Attainment of nirvana was thought to equate to the end of suffering, as well as enlightenment.
My tradition, Nichiren Buddhism, believes that perfect enlightenment has always been the goal. In the Lotus Sutra the Buddha states that he taught many different paths to appeal to many different kinds of people, but that ultimately they all become the same path towards enlightenment. Practicing this path, also known as the One Vehicle, individuals are concerned not only with their own progress on the path but that of others as well. Rebirth, under this view, is another chance to continue assisting others on their paths as well as making more progress on our own path. Thus rebirth is not something to avoid or escape.
Rebirth is also distinct from reincarnation; the two terms are not interchangeable. Reincarnation signifies the return of an individual; rebirth does not. Rebirth signifies a new being; there is a certain continuity from the previous, in the form of karma, but they are not two instances of the same individual.
Emptiness, or the lack of a "self" is exactly the concept here. Basically it means that there is nothing that is absolute/eternal/unchanging. Because this is so, there is no "self" which continues from life to life. However, karma is passed along, so it behooves us to create the best possible karma we can to pass on to the next individual "we" become, whether that involves attaining nirvana or enlightenment.