I've been on a steampunk kick lately and enjoying it. I put together some steampunk wallpaper earlier today and was looking for more stuff, when I decided it would be good to develop a method to make something real into steampunk.

I grabbed a picture of the Hadron collider and went to town...

Click image for larger version. 

Name:	Steampunk Wallpaper.jpg 
Views:	60312 
Size:	3.16 MB 
ID:	22336

1) Find picture of machinery you want to "steampunk".
2) Desaturate it.
3) Add a layer below and cover with the color and texture of parchment you'd like as a background color.
4) Go back to the machine layer and change the the layer style to "multiply".
5) Merge the two layers.
6) Image/Adjustments/Brightness/Contrast - bump down the brightness to taste and bump up the contrast.
7) Filter/Noise/Add Noise/25% Gaussian.

That's it