I don't have any artwork but a catchphrase for a G&FH SE ad on the GIS Stack Exchange, which has about 6068,000 registered users, could be:
Where's your ancestry?
Over the past 10 or so years the GIS industry has made a concerted effort to "own" the word "where" and so it would help associate the subject matter of the two sites.
With Family HiStory Mapping being a focus of mine I would love to see more GIS Professionals taking an interest in Genealogy & Family History.
Perhaps a graphic could be a globe of the world centred on the Atlantic Ocean (so the Americas, Europe and Africa are all visible), with a few bright yellow stars at locations like New York, the Carribbean, West Africa and London, and a 19th century ship placed in the centre of the ocean, and maybe a double helix to represent DNA placed somewhere else.