Wrap your book with an interesting cover. Designing a cover on Bubblin is much simpler than it is elsewhere. You can use our own PSD cover and spine templates to design the top, bottom and spine of your book (available under MIT License). Also feel free to use and redistribute.
Always save_image_for_the_web and optimize your PNG/JPG image using compressors like OptiPNG or jpegTrans. To change the cover of your book simply replace simply by reuploading a new image.