Mirrors are funky and really fun to play with in photography. There are some really fun images you can create with a reflection. While mirrors are the topic, it would be wrong to exclude reflections. This could be a self portrait or a more unique look at how mirrors can alter ones perception.
Some of my favorite images of reflections are where the mirror acts as a portal to another image within an image. A simple google search will bring up a bunch of ideas for you to try.
As always be sure to send your image and its story into firstname.lastname@example.org for a chance to get featured!