I was watching the first season of Powerpuff on DVD the other day and I sketched down a crappy little Sedusa on a post-it.
Then I came across a fancy little photoshop brush on Justin Ridge's blog which he actually got from another guy whose name I don't remember's blog. It's called the stumpy pencil.
Put them both together and you get this! I used the stumpy pencil for the subtle grainy look on the shaded areas and around the white heart border, though it's kinda hard to tell looking at low res version. It was pretty fun to use if I might say so myself.