Since its introduction in January, the Kotaku 'Shop Contest has been a popular weekend feature. If you're looking to brush up your skills creating a subject marginally relevant (spoiler alert) to tomorrow's challenge, here's an excellent tutorial.
Power commenter Deanbmmv sent along this step-by-step how-to for making box art reminiscent of the 1980s console days. Although very specific to a certain genre, the effects it teaches you could be useful for future projects. And plus, the final result is period-perfect and just damn cool.
Note, you will probably need some very well known illustration and image-editing software to pull this off, perhaps rhyming with "Schmotoshop," not that we would ever use that trademark as a generic verb.
How to Create a Retro Sci-Fi Computer Game Poster [Spoon Graphics, thanks deanbmmv]