My lovely colleague NT found this.
How it works: you type in a slogan, and it comes out in the style of the atheist bus ad.
Write one of your own in the comments, and if it's any good, I'll wack it up here as a pic. Can't promise to do them all though, as I am a bit hung-over.
Here's one, from 'Anonymous'
Here's three more. All from our old friend 'Anonymous'