Open background image. Here we used 400 X 250 pixels at 72dpi.Copy this image to your computer or use your own.

Create a new layer. Press “D” to set default foreground and background colors. Go to Filter > Render > Clouds.

Filter > Stylize > Find edges

Now adjust the levels for more definition in the image: Image > Adjust > Levels or (Mac:Command+L / Windows:Ctrl+L).

To create the drops: Filter > Sketch > Plaster. You will have to experiment to find the best settings for your image size and intensity of the effect, here we used: Balance 40, Smooth 14, Light - Top Left.

 To define the edges a bit more: Filter > Sharpen > Unsharp Mask: Amount 500, Radius 1.0, Threshold 0.

Select the magic-wand tool, Check the contiguous box on the status bar if using Photoshop 6.0, otherwise it is in the options palette. Set the appropriate tolerance setting,  we used 10. Now select the background around the drops.