Cat slumped over the keyboard a sleep, with the words "donationcoder.com is my life, and what a life" typed on the screen, a coffee mug with donationcoder.com written on it, not forgetting the t-shirt emblazen with "donationcoder.com"

And maybe the phone ring appearing to ring in the background

I definitely think the mascot has to be an uniquely identifiable character rather than a generic object such a keyboard, computer or suchlike.

I also think there shouldn't be too much going on in any of the logos E.G. a cat coding whilst connected to the internet, drinking coke, smoking a cigarette with a TV on in the background, phone ringing, donations coming through the letterbox and dinner burning in the kitchen - though it probably would accurately describe some of us here (minus donations). 

Simple and effective is the only way to go.  A cartoon cat at a keyboard does have a certain charm and hopefully does get across the spirit of the site.