Is there a simple way to create a 3D looking cardboard box to show off what some packaging might look like. Photoshop solutions would be helpful. I would like to be able to change the images on the sides.
There are couple of options in Photoshop:
Although you mentioned Photoshop, Illustrator has can extrude shapes and also apply symbols as textures, so you could easily draw an extruded box and use the faces of the box as symbols. Here's a quick video tutorial I recorded on this technique. This works assuming you have a basic box design. For more complex designs have a look at the FoldUp plugin.