This is my first tut, so any comments, criticism, etc. is welcome...
And sorry 'bout the no screencaps thing. I sorta forgot to do that.....

OK, first create a new document, 400x150 or whatever size you want you sig to be. Then FILTER>>RENDER>>CLOUDS. Redo till you're happy with your clouds.
Next, FILTER>>STYLIZE>>WIND. Change the method to BLAST, and apply it once EACH from the right and the left. This step is VERY important!!

Then FILTER>>DISTORT>>TWIRL. Amount=160 or so...

Press ctrl+B to bring up colour balance. Change the values to 0, 20, 100. Then duplicate your layer, change the mode to lighten, and merge the two layers. ctrl+B again, insert values of 0, 40, 100. Merge again.

Duplicate your layer again. Go to FILTER>>DISTORT>>WAVE. Default settings are fine, just change TYPE to SQUARE. Another important step. Set this distorted layers mode to DIFFERENCE.

Looks neat, eh?

Now you've got your wall. It looks pretty good by itself, but lets add some text...

I suggest you use Comic Sans MS here. Anyways, take a dark shade of the colour you wanna use, and give it a 2px stroke of a lighter color. Duplicate the layer. On the LOWER layer, do a FILTER>>DISTORT>>RIPPLE of amount 999 and size medium. Do this twice.

There you go!! Play around with the blurs to get something you like!

TIP: Transform the text a bit, and put multiple slogans/words/etc. Experiment!

Hope the tutorial proved to be of some help...and sorry about the screencap thing once again! :unsure: