This is a simple shader example of a futuristic rainbow with subtle grid lines. The shader has a few different example lines with explanations on how it works. There is a line, that goes across the center of the screen and wiggles with a sin wave. There is a circle version that expands, and a few others.
The shader works at pretty much any resolution. This little project also shows examples of how to do resolution independent drawing (for both the main draw event and GUI draw event).
Feel free to use it in any project that you wish, once obtained.