In addition to Bigify, which is free, here is Bigify+
Bigify+ is even bigger than Bigify! It can make your icons look blue and icy, inverted and strange, even cracked like pavement. Those are just a few examples. We added a ton of new features like a preview window, a colorizer, and textures. Just look at the screenshots and see for yourself.
Also includes all the features of Bigify:
No new icons are added to your homescreen. Options are configured from Settings.app