Much to my dismay, I used to be an Anne Rice fan as a wee teen. I latched onto the barely-used character of Mael, inverted his name, took to writing it in ALLCAPS because it looks like a cool acronym, and appended my year of birth to it.
As for the "Iam" part, that's to circumvent my forgetting my password for my first version of that alias, which was just LEAM1983. It was basically me going "Hey guys, it's me!" with my then-regular gang of text-based roleplayers.
I have two generic usernames which I tend to use often. If I can't use "LEAM1983" or "IamLEAM1983" for whatever reason, I tend to use "WeaselBiggs", as this is the name of one of the characters I play.
On the off chance that none of the above work, then "rodentmafia" is used instead - which is kind of an indirect callback to Weasel Biggs.
...
Yeah, I was pretty young. Weasel's original concept was as an anthro weasel dressed like Vincent Vega who happened to be an extremely cliché mobster. I think I'd just played "Conker's Bad Fur Day" or something, when I first designed him. Years passed, my writing and reading chops expanded, and while I can't retcon Weasel out of the board's canon or remove him easily, I have managed to add enough layers of complexity to the guy to make him out to be something other than a GoodFellas reject.