The physics of bird song, the effectiveness of background noise to improve concentration and the necessity of drinking water after a massage are unusual science fair topics. The chemistry behind glow sticks and the science behind Harry Potter's magic are other unique options.
Birds make very distinctive noises depending on the species, the gender and the time of year. One science fair idea is to choose a bird and examine how the animal makes the different sounds. Students need to examine what mechanism is used for the different sounds and if the bird has multiple independent resonators.
Students typically like to listen to music or have the television on while studying. For a science fair, they could study whether background noise actually improves or hinders concentration.
People who get massages typically hear they need to drink a lot of water to flush out the toxins loosened up by massage. Students could research the science behind this advice. The necessary information for this topic includes whether toxins build up in the muscles during stress, whether massage loosens up the toxins and whether they're flushed out by water.
Glow sticks are a popular party favor. Students can outline the chemistry involved in the luminescent liquid. Another unique option is examining some of the science behind Harry Potter's magic by making disappearing ink or fuzzy potion.