This tutorial will teach you how to create an interesting 'ghost' like effect. It isn't actually ghosts as in haunted house ghosts, you will see what I am talking about once you finish this tutorial.
1. Open up a new image (File--> New) and give it a width and height of 300px, then press OK. Press D on your keyboard to reset the colours. Then go to Filter--> Render--> Clouds.
2. Next, go to Filter--> Liquify. Press W on your keyboard to select the Warp Tool and use these settings on the right-hand side of the window.
3. Press ctrl+L to bring up the levels box. Press Auto to adjust the levels automatically and press OK.
4. Go to Filter--> Stylize--> Find Edges.
5. Go to Filter--> Blur--> Motion Blur and set the Angle at 0° and the Distance at 50 pixels.
6. Again, press ctrl+L to bring up the levels box. Press Auto to adjust the levels automatically and press OK.
7. Press ctrl+U to adjust the Hue and Saturation. Check the colorize box and fiddle around until you get a colour that you like and press OK.
8. Right-click on the layer in the layers palette and go to Duplicate Layer. Leave all the settings at default and press OK. Set the new layers blending mode to Overlay.
Done! There are ways that you can change this, such as using different settings in the Motion Blur box in step 5 and using different brushes and things in step 2. If you create miltiple layers using this same technique and set the blending modes to overlay or somethign similar, you will get a much more enhanced effect. This tutorial only shows the simple part, the rest is up to you and your creativity.
This is what I came up with following this tutorial:
And with a little variation, I came up with this:
