You can download GIMP, it's something like PhotoShop. It takes a little bit to learn, but it's worth it. You can also do some simple stuff in either PowerPoint or Word.
Print them on a high quality paper - a bunch will fit on a single sheet, cut them, spray them with hair spray and adhere them to the bottle with a glue stick.
On Tap: Whatever I just brewed (got sick of updating it)