Want to become the next big name in science? It’s easy: “solve one of these nagging questions”:http://www.newscientist.com/channel/space/mg18524911.600 and you’re almost guaranteed a Nobel prize.
I particularly like number 4, the effects of homeopathy. I actually use homeopathic remedies, and some of them have worked well. I just try not to dwell on the official explanation of why they work. (Bonus points for answering both 1 and 4 with the same theory.)