Sunglasses make awesome filters to jazz up any photo that you want to take but are looking to add a more of an artisict touch. I use this technique with my phone camera all the time.
Think about it. You buy a polarized lens for your camera, which is basically sunglasses for your camera. You also buy polarized sunglasses for your eyes. Why not use your resources and create art?
The closer you hold them to you phone camera the more subtle the filter. You get the same effect you see when you wear your sunglasses or if using a polarized lens.
And if you hold them further away from your phone and tilt the angle of your glasses you can get some pretty trippy effects.
It's a very simple way to take your photos to the next level.