I recently did a logo redesign for a company that used a version of the Eye of Ra in the logo.
I read up on it and decided that it could make a lekker tshirt.

The actual Eye of Ra is the eye on the right (The Sun). The other represents Tehuti (The Moon).
Together, they see everything!

—- Excerpt from About.com —-

According to legend, the left eye was torn from Horus by his murderous brother Seth, and magically restored by Thoth, the God of magick. After the restoration, some stories state, Horus made a gift of the eye to Osiris, which allowed this solar deity to rule the underworld. The story of this injury is probably an allusion to the phases of the moon as the eye which is “torn out” every month.

To read more about the the eye of Ra, follow this link:

http://altreligion.about.com/library/glossary/symbols/bldefseyeofhorus.htm