Editorial design has for me is the biggest source of inspiration.
Xavier Esclusa Trias has created a poster series that is bringing a bit of a nostalgia moments to be honest. Pure throwback from the days where we didn't care about going to rent movies at the video store, where the packaging was just part of an item that you will eventually learn to appreciate. From what Xavier created, I just dig there aren't any 'special effects' like gradients, shadows, or whatnot. It's all graphical shapes and typography; there is something about having to work within these past constraints.