I don't know if there's any real useful purpose for these, but I made them pretty much just for fun. They're just banners for all the Firefly characters with a quote either made by them or about them. The quotes are supposed to be interesting or funny so that they make you want to learn more about the characters. (Perhaps as part of the guerrilla marketing.)
If you want to use them for anything, either credit starfleetcadet or link back to this post.