I suggest that you read up on Dr. Josef Mengele of Nazi Germany. He was infamous for his experiments on humans. You could get some good ones from that monster. Or you could read : The Boys From Brazil and have a good idea.
I'm currently writing a novel about mad scientists, human test subjects, that sort of thing - does anyone have any suggestions of experiments they could perform on humans? Cruel, or not - use your imagination.
Something about mythological hybrids. Attempts to create angels and centaurs and minotaurs and satyrs and what not. Human-animal hybrids from mythological tales
Maybe look into splicing. I know people think 'okay, mix human DNA with animal', but you could do something different like human/plant or human/chemical. It would definitely be unique.