Mudrooms are generally small, narrow spaces. The blue on the door in this mudroom brightens up the space and adds a dash of personality.
There are a lot of interesting things happening in this entryway: the barn door, the modern light fixture, the staircase. Even with all of that, the jolt of chartreuse makes the door the star of the show.
If you're feeling adventurous, don't limit yourself to a single color for your doors. Choose a scheme that works for your home and have fun.
Even traditional spaces are more interesting with painted interior doors. This black door draws your eye to the artwork on the wall and the lovely room just beyond the doorway.
This painted barn door becomes even more interesting with the lovely pop of color.
An old door spruced up with chalkboard paint and used as a piece of artwork adds instant drama to this bathroom.
Consider adding complimentary colors to adjacent doors like the ones in this image. They are far more interesting than if the doors were all painted the same hue.