David Garrett Arnold.
Not afraid to use my full name 'cause it's all over the 'net anyway. But "Nam" is my actual nickname offline. Everyone calls me "Nam" but family, who call me "David" and those rare few non-family members who also call me "David" or "Nammy" out of affection (yes, there are people who have affection for me who I am not related to and did not force to; and yes, they must be insane). I have had my nickname for almost 16 years.
And just to let everyone know: I prefer "Nam".