Uhm, well, it's a story.
Moira means a lot of things. First of all, I really like the name and it's much like the name I will take when I change it officially (that name being Maria). Moirae is a term for the Fates in various mythologies. I sign my posts with Moi (french for "me"). Oh, and Moiraine is my favourite character in Robert Jordan's Wheel of Time series. Moira is probably also going to be my artist's name when I release an album.
The Midnigh part is also complex. I have been Moira-at-Midnight other places, since I rarely log on anywhere until it's 11 o'clock here, which makes it 12 o'clock for anyone a little further east than me. So that earned me the nick Midnight. Midnigh was, originally, a spelling error in Guitar Hero (naming my band, y'know), but it just stuck. Since I'm always on close to Midnight, I.e. Mid-nigh.
Put them together, you get moi. Also, I am quite fond of the letter M.
Revived the old thread, yeah, but I had considered starting my own anyway, so this was the lesser evil. I think it's always fun to see where people get their inspiration.
~Moi