I am currently making the album artwork for my friend's CD, and I need a bit of help. Does anybody know of a free GIMP or Photoshop plug-in/strategy to create a sound wave/sonar effect? To describe this a bit, I'm talking about an effect that generates a series of circles that grow out from a center point, like in this image:
Thanks for any help.
EDIT: Oh, and I have tried to manually draw the circles (this was during my first attempt a couple months back), but since then, I have upped the resolution for the CD cover, meaning that I'd have to draw in more circles than I did than before (I'm too lazy to do that

).