I remember meeting a particular religious guru at the age of 19. During an interesting chat that we were having concerning Hindu mythology and shlokas, I asked him what exactly the Gayatri Mantra meant.
He told me that the shloka referred to the various body parts of the Mother Goddess and that it is a hymn to ask Her to radiate energy from her entire body to us.
Today, I found a picture on the Net, alluding to the same:
Wikipedia offers other explanations / translations of the shloka here.