I'm thinking of one for my 4 way vertical build but have not yet made it a theme.
It will be based around the phoenix arcade game and once I settle on a final game list I'm going to download sprites for some of the more well known games and incorporate them.
But I'm working on getting the cabinet built right now.
But if I understand correctly the themeing process you could just grab the background image from just about any front end out there and tell attractmode where to put the list, images and info for a basic theme.
Not sure about wheel themes, may take some editing of the background image.