Well, as long as I've remembered I've been kinda moody and melancholic (although I had a professional confirm that at least I'm not clinically depressed). I also listen to trip hop (Portishead, Lamb) a lot and I remember thinking "When I release my first album I'll call myself 'moodster'!", because it seemed a good name for an artist.
in reply to Name Space
Then I realized that I would never actually release a record. However, I could do the next best thing and use the name as an online handle... :)