Photonic Metamaterials are novel materials that consist of subwavelength optical resonators called meta-atmos. They have attracted much attention, due to their ability to control and confine light. In particular, they have promising applications in color generation and nonlinear optics. Here, I give one example for each of these two applications. Chapter one presents an actively tunable full-spectrum device. An array of plasmonic aluminum particles is integrated into a stretchable polymer substrate. Stretching the substrate in either of its two dimensions causes a change in the array period, and therefore changes the associated scattering color. Using a two-dimensional stretching approach, I demonstrate full-spectrum tuning, as well as image switching. In chapter two I present an all-dielectric metamaterial consisting of an array of zinc oxide (ZnO) nanodisks. The material shows a magnetic dipole resonance around 400nm. When pumped at resonance, the associated field enhancement can be used to generate the second harmonic frequency. This serves as a first demonstration for a simple device to generate deep UV light.