i think we just call it the "at sign." boring, huh?
howstuffworks gives examples of what other cultures call it:
apestaart - Dutch for "monkey's tail"
snabel - Danish for "elephant's trunk"
kissanhnta - Finnish for "cat's tail"
klammeraffe - German for "hanging monkey"
kukac - Hungarian for "worm"
dalphaengi - Korean for "snail"
grisehale - Norwegian for "pig's tail"
sobachka - Russian for "little dog"
i use it for panda eyes @_@ hehehe.