Cloning would be child's play in the Star Trek universe.
Transporter technology could easily make copies of individuals. Their patterns are kept in the transporter's memory buffers. Such technology would also be useful as a medical instrument. Why they didn't put Worf in one during the episode where he broke his back is beyond me. They could have used his last transporter pattern to easily fix his spinal cord. It would also make a great immortality machine.