A fun way to say "Oh my God" Some people find it annoying, which makes it even more fun to use. Some people feel it's using the lords name in vain, but as you can clearly see it's spelled gawd, not god, so no, it's not taking his name in vain.
Originally added on to omg to make it seem like the thing being omg'ded was of low likelyhood of happening. The word originated on World of Warcraft when the player deadonsight of the forgotten coast realm screamed it on ventrilo. The word has been coined by many users of many games ever since.
"omgawd, did you just see him one-hit-ko our tank?"
Omigawd, which is usually meant to be a very annoying teenage girl crappy xanga blog word, means "Oh my god" in a crappy xanga blog kind of way. Also used by teenage girls on AIM. Omigawz is also an equally annoying way of speaking thy Lord's name in vain.