Sometimes you want to do some post processing on a photo so that it looks a bit different. For example put some good old tobacco stains on your moustache.
The easy way to do this is by using textures and on Ipernity there are a few people who have graciously made their textures available in the Textures Group
For the portrait on the left I have used a couple of textures
1) Noise and dust through the viewfinder polaroid
2) A steamy window I shot on a midnight bus ride home which is responsible for the little neon flickers on the shirt.
I have been impressed by the camera obscura work by Marja Pirilä She uses a camera obscura to generate images on the walls of rooms and then she takes a normal photo of people in the rooms. Some of of her photographs are gorgeous, and it is well worth a look at her site to see more of her style.
So I tried to achieve that effect with the photo on the left using this photo as the texture. The obvious mistake is that I have not inverted the photo, since all camera obscura images are upside down. All of the work was done with GIMP