Bullet Train
The 500-series Shinkansen Japanese bullet train running between Tokyo and Hakata is one of the fastest trains in the world. It drew its inspiration from owl plumage to reduce air resistance noise and the air piercing nose cone design was inspired by the kingfisher's beak. Owl has saw-toothed wave feathers; they generate small vortexes in the airflow that then breakup the larger vortexes that produce noise. The shape of kingfisher's beak is aerodynamic. Scientists observed the aerodynamics in it and designed the front part of that train like the beak of kingfisher bird.
Lotus Paint
Lotus leaf, due to the presence of wax, does not retain any water or wax on its upper layer. This is called lotus effect. Based on lotus effect a paint named Lotusan is developed by a German Professor Wilhem Barthlott, from the University of Bonn, which is dirt and water repellent. It has self cleaning properties and excellent resistance to weather, chalk and UV rays. It remains clean even for decades.
Shark Suit (Speedo Fast Skin)
Fast Skin Shark suit is designed by Speedo based on the scales of shark. It has been observed that the reason for the ability of shark to swim fast is nothing but the design of its scales. The shark suit is designed this way to help swimmers by Based on this shark suit is designed which helps the swimmers to swim fast by reducing water friction.
Gecko Tape
Gecko tape is a gum less tape designed by the Manchester University Scientists. This is designed by the inspiration of the Gecko lizard's ability to climb up walls and walk along ceilings. The Gecko foot has tiny hair-like structures called setae that exhibit van der waals forces.
Mercedes Bionic Concept Car
Mercedes bionic concept car is designed based on the body shape of a boxfish. Boxfish is found in tropical marine habitats. The car has hexagonal shaped body which has less weight and all its parts are also lighter weight. This car can travel 60 km. within eight seconds only. It emits 80% lower nitrogen oxide and consumes 20% lower fuel.
Velcro
Velcro is the famous brand of the hook-and-loop fasteners that were designed by Swiss Engineer George de Mestral in 1940. He designed it after the observation of how the hooks of the plant burrs stuck in the fur of his dog and his pants. Observation of this under microscope showed him numerous tiny "hooks" that belonged to the plant.
The Eastgate Complex
The Eastgate ComplexThe Eastgate Complex located in Harare, Zimbabwe was designed by the Engineers of Arup led by Mick Pearce. This complex is designed with the inspiration from the ventilation design from termite mounds. Termites require their home to remain at an exact temperature of 30.5°C throughout the day even when the temperature ranges from 1°C (during the night) to 40°C (during the day). This complex has natural cooling ventilation process with specially designed hooded windows, variable thickness wall and light colored paints to reduce heat absorption.
Turbine Blades
Flippers of the humpback whales are very efficient in propelling the whales forward despite being so huge. The tubercles of the flippers are the reason for this hydrodynamic efficiency. Biomechanist Frank Fish incorporated this design in Wind Turbine blades and has observed that they produce more energy and less noise at lower speeds compared to their normal smooth edged counterparts.
Smart Fabric
Smart fabric is developed by Britain Researches at the University of Bath's Centre. This new fabric is developed based on the mechanism used by the pine cones to shed their seeds. The smart fabric does the same thing, opening up when it is warm, and shutting tight when cold.
Cat's Eye Reflectors
After studying the tapetum lucidum, the reflector cells in cat's eyes that reflect even small amounts of light, Percy Shaw in 1935 designed reflectors that are now being used on roads to mark road margins and lane dividers. The reflectors usually consist two reflector glasses fit into a white rubber dome. This dome is fortified by mounting onto a cast iron holding.
I'm pretty sure that there are many other unexplored designs in nature that would someday be the inspirations for novel products and designs.