“My Galaxies” lets you spell out anything you want, using real galaxies that are shaped like characters.
You can read more about it at the site and/or at this MSNBC story.
The site does what I describe — you write a message and then it uses images of galaxies that look like the alphabet to spell it out. You can then send the link or post it.
The story behind the site is very interesting, so I’d encourage you to read more about it at the above links.