Hey, you! Yes, you, with the pony!
Do you have a jailbroken iOS device? If so, you should totally check out this complete pony overhaul. It's from a pony named Ziddia and it replaces, as far as I can tell, the lock screen and the icons for the default apps.
From the email:
It's been added to a repository you can test from at http://www.cydia.myrepospace.com/ziddia, and it's also being added to TheBigBoss as I type this. (Again, just in case you didn't know, that's pretty much the biggest source around, it comes with the installation of Cydia).
It's the only package in the myrepospace repository, so it's not that difficult to find. I've tested the installation myself, it's working perfectly and installs directly into Winterboard as it should.
Kind of makes me wish I wasn't so nervous about jailbreaking my iPad.