Gree-bo easy really. Back when I was internet newbie and had zero imagination for my very first email addy (which I still have) I chose the name of one of my cats who obviously was named after Terry Pratchetts Greebo. Of course, in retrospect, maybe naming myself as a grotty old tom cat that shags and/or fights anything that moves was not the greatest of ideas. Especially as I'm female :) And just as a side note, I have the user name of Nanny Ogg over at the site that can't be named :)