The Picture of the Day is a feature on the main page. It is a way to feature particularly interesting pictures from the wide range available in comics, games, episodes and movies and giving some attention to the corresponding articles. Currently there are 6,027 images in the Memory Gamma database.
There is no nomination process at this time, just find a empty link in the box to the right, and pick an interesting Memory-Gamma image. The general image rules apply: properly named, cited, and with correct license boilerplate. Images should not be uploaded purely for use as a picture of the day.
Fill in 1, 8, 15, 22, and 29 first, because those are fallback positions for days that have no picture defined yet (Pic of the Week, in that case).