Been working overnight shift at hotels for years. The "night audit" shift.
At the time I chose my name, The Screen Savers was still going strong on TechTV (Curse you, Comcast!), and Kevin Rose had a segment known as the Dark Tipper. I combined the two and became... DarkAudit.
It has the advantage of being unique enough that I've never seen it used elsewhere by anyone other than myself. So if you see another DarkAudit around, it's probably me.