I've got a major editing job to tackle today, so to inspire you, here are some of the covers I've made over the years for my promotional e-books, writing and quilt workshops, and the collections of my private work.
Art that you create to promote your work or inspire you while you write doesn't have to be elaborate or complicated. Half the covers I've made are just background photos with a title and byline. The idea is to have fun with it and create something that reflects what you see in your head as well as what you write on the page.
If you've got some art you'd like to share, post a link in comments (and please, be sure to note if it's not work-safe.)