Rebirth and similar concepts are not a part of most westerners' cultures, so many western Buddhists, as well as some eastern Buddhists, take rebirth as a metaphor, rather than literally. Buddhism has never been a particularly literalist religion, so this is not at all taboo. In fact, Buddha often avoids discussing the reality of one metaphysical idea or another as irrelevant to the practice of the Dharma.
The image to the right is the Tibetan Wheel of Life, which represents Samsara. In the very center, there is a rooster chasing a pig chasing a snake chasing the rooster -- craving, hatred, and ignorance. Around that are people ascending the white semicircle of life, and others descending the black semicircle of death. The greatest portion of the Wheel is devoted to representations of the six realms -- the realm of the gods, the realm of the titans, the realm of humans, the realm of animals, the realm of the hungry ghosts, and the realm of demons -- each realm looked over by its own boddhisattva. The outermost circle is the 12 steps of dependent origination. The entire Wheel is held by Yama, the Lord of Death.