Last year I started using those small shelves from Ikea to display books in my classroom. I don't remember how much they were but they are super easy to install and are very sturdy. Since we study ancient civilizations in 6th grade, I would display books to go along with whatever we were studying: ancient Greece, Rome, China, Egypt, etc. I figured that for 5th grade I would try to display different genres and switch them out every few weeks to help the students understand them better. I used the free genre poster download from Beth Newingham (who coincidentally inspired me to start a classroom economy years ago).
My photo isn't the best, and there is an inconvenient glare, but I currently have up Informational, Mystery, and Realistic Fiction. My hope is that they not only better understand genre, but maybe they'll pick up and read some of the books I have displayed. Books are so much more welcoming when you can see the front cover and not just the spine!
I am also planning on adding an insert to the students' Read and Respond that includes a handy guide to genre.