James Bit. Just email him with the name of the game and its platform (he does DVD covers as well) and he emails you a PDF of the cover. Then its a simple process of printing the cover and slipping it into the case. Six dollars gets you three covers, but on larger orders, he only changes $1.49 each. They'd come in handy if you've ever bought used games from a GameStop and didn't come in their original case or if you just want something different.
Picture via bonerack. h/t Laughing Squid.