Infrared photography
In infrared photography special filters are used which block visible light (and ultraviolet light), and only infrared light is recorded. It's really intriguing to be able to capture stuff that we can't see with our own eyes. Especially foliage and grass shine really bright, giving an almost wintery look to the pictures, even when taken in midsummer. Some more information on infrared photography can be found here.
These photos are made either with a Nikon D80 or a Nikon D5300, which I converted myself by installing the cold mirrors in front of the sensors as is described on Lifepixel's website. The conversions were not too hard, but doing it dust-free proved to be impossible in a home environment, so I had some dust particles immobilized on my sensors.