Dripping Slime
Use this tutorial to create rust, slime, or blood dripping from holes, pipes, or text.

1
Create a new image with equal height and width. For example, 500x500 pixels.

While holding down Ctrl, click on the layer you want the dripping applied to. This will select the layer's opacity.

In this case I've selected some text created with the type tool.

2
Press Q to enter Quick Mask Mode, and then press Ctrl+A to select all.

Edit > Transform > Rotate 90^o CW

3
Then, in the menu go:
Filter > Stylize > Wind...
Press OK.

If you want the rust dripping farther down, press Ctrl+F to repeat the Wind filter.

Edit > Transform > Rotate 90^o CCW

4
Now, press Q to exit Quick Mask Mode. In the Layers window, click on the layer right under the text, or object you are applying the drips to. In this case it's the layer named Background. Now, click on the Create New Layer button , to create a new layer.

Select a Rust color as the foreground color, and then press Alt+Backspace to fill the selection.

Press Ctrl+D to deselect.

Try to spot the dripping rust in this image.