I was on a webinar today and the photographer showed some ideas on combining different "looks" to create novel views.  The combinations explored today were photographs merged with line drawings, something that is easily done in Photoshop using the Filters and Layers capabilities.  Here's an example:

This is simply two layers.  The bottom layer is the original image and the top layer is the image put through a Filter that renders a sketch version of it.  I chose a blending mode (Darken) to combine the two and then ran the final image through a couple of NIK filters to lighten it up and bring out some details.  I like how it delivered a sort of pastel look to the image along with some false colors.

Playing around with photographs it's easy to forget there are other visual means of portraying a composition.  In the early days of photography some painters would paint over their prints to give color (the days before color photography) as well as bring out specific details they felt were important to the composition.  Today I saw some examples of city skylines that were enhanced with this technique and it really gave dimensionality to the image.  Something to keep in mind for other types of photography.