Robotic sexual partners, I think they'd reduce the amount of spree killings, school shootings and instances of child molestation. A great many ills in society can be traced to sexual frustration, because of how tied up sex is with male identity.
Perfect cloning of an individual, this is my biggest dream of all, I want a perfect copy of myself to raise from childhood.
I would say I'd love to see Dinosaurs brought back. But we have no way of knowing what they eat, no way of guessing what kind of environment they'd find agreeable, and could only offer them a life in captivity. So, whilst I find the idea amazing, in practice, it would be rather cruel.
It's the same problem I have with bringing back the Woolly Mammoth, I'd love to see them, but only if we could offer them a happy life.
I'd love to see some way to alter the make-up of humanity. Allow us to regrow our teeth an infinite amount of times, bring back the tail we lost, widen the scope of hair and eye colour. Cosmetic changes that could allow the individual to become all that they wished to be. No one should have to be ugly simply because of their genes.